The winter transfer window in Europe opens on Saturday, Jan. 1.

MLS will again play an important role as the world's biggest clubs continue to scout players from these shores who find success on their next stage.

This winter will be no different. Keep an eye on these MLS players.

Almost definitely leaving

The 2021 Golden Boot presented by Audi winner and an MLS Cup champion, Taty Castellanos is set to leave the league on an absolute high. It'd be borderline shocking if he was still on New York City FC's roster come Feb. 1.

But questions remain: Where? And for how much?

Brazil's Palmeiras have long been admirers of Castellanos and, according to ESPN's Jeff Carlisle, had another bid of around $12.5 million rejected this winter. According to Carlisle, NYCFC are holding out for $15 million. That would be among the biggest outbound transfers in league history. With plenty of clubs in Europe interested, and Manchester City manager Pep Guardiola giving his stamp of approval, $15 million seems like a reasonable ask.

NYCFC's decision to reject offers of around $5 million from Palmeiras last winter and sign Castellanos to a new contract could not have aged any better.

Castellanos, 23, made his MLS debut in 2018. He had 19g/8a in 32 appearances this season, winning the Golden Boot and earning an MLS Best XI spot. He has 37g/18a in 92 MLS regular-season appearances.

Like with Castellanos, it'd be a huge surprise to see James Sands with NYCFC when the January window closes.

Sands has been linked with Scottish Premier League side Rangers, and sources say NYCFC have held talks with European clubs over the future of Sands.

The 21-year-old defensive midfielder/center back has 65 MLS appearances after becoming the club's first-ever homegrown signing. He made his senior US men's national team debut this summer as well. MLSsoccer.com has previously reported that clubs in Europe hoped to sign him and this winter might be the time to go. Even sporting director David Lee admitted that to The Athletic's Sam Stejskal.

"I think we’re open [to offers]," Lee told The Athletic. "We’re working with James. I think, like all players, every player wants to test themselves at the highest level that he can. And if an opportunity arises that we think is right, that James thinks is right, then we’ll consider it. And that’s our commitment to James, and I think it’s the right thing in terms of players to ensure that we’re going to help meet their ambitions and career goals."

Expect Sands to depart this winter.

The saga of the offseason, reports over the future of FC Dallas homegrown and USMNT forward Ricardo Pepi are aplenty.

German Bundesliga side Wolfsburg are in advanced talks over Pepi, but nothing with Dallas has been agreed upon. They're not the only team involved, so this is far from over. Dallas were determined to keep him as the offseason began, but their stance seems to be softening with big bids swirling.

Pepi, 18, had a breakout 2021 season in which he scored 13 goals in 31 appearances, was named to the MLS All-Star team and made his USMNT debut, already notching three goals and three assists in World Cup qualifying.

A cascade of big European clubs have expressed interest in the forward, including Bayern Munich, Real Madrid, Ajax, English sides and more. Dallas aren't rushing to agree on a deal, with the transfer window only officially opening now and Pepi likely to be at USMNT camp in mid-January anyway.

Inter Miami's club-record signing Rodolfo Pizarro is on his way out.

A source confirmed a report from the Miami Herald's Michelle Kaufman that Miami have agreed to send Pizarro back to Liga MX's CF Monterrey on loan with a purchase option. The deal is very close to being done and includes some incentives.

Pizarro, 27, never quite found form in MLS, with just 7g/12a in 46 appearances with Miami. The Mexico international originally joined Miami from Monterrey. He also had stints at Pachuca and Chivas earlier in his career.

The move could either open a Designated Player spot for Miami or they have options in how they will finesse and maneuver along the cap.

More likely than not?

After rejecting a potential club-record move to Portugal's Benfica in the summer, Cole Bassett has been expected to move this winter. Already blessed with an incredibly deep central midfield group, the Colorado Rapids selected the rights to former Dallas DP Bryan Acosta in the Re-Entry Draft last week. It looks like they expect Bassett to move, too.

Sources say clubs from the Netherlands, La Liga and elsewhere remain interested, as well as those from England. It's likely he'll qualify for a UK work permit, thanks to his senior US national team debut this month (in which he scored the game-winning goal in a 1-0 win over Bosnia and Herzegovina).

Bassett, 20, has already accumulated 72 career MLS appearances in three-and-a-half seasons. He has 13g/11a over that time, producing strong numbers for a box-to-box midfielder.

Fellow homegrown Sam Vines transferred to Royal Antwerp in the summer for $2 million. Bassett's final fee should easily eclipse that.

After lighting up the English Championship while on loan at Barnsley, igniting a frenzy of rumors that even Dike himself chuckled at in hindsight, it was overwhelmingly expected that the forward had played his last game for Orlando.

But a summertime transfer just never happened. Things may be different this winter.

The latest reports from 90min's Chris Smith and locally in England suggest Championship side West Brom are chasing a loan-with-purchase-option offer, while Leeds United are interested as well. West Brom sit fourth in England's second division, four points off an automatic promotion spot to the Premier League.

It's worth noting that over the summer, Orlando were in the midst of an ownership change. That probably complicated his future at the time. That's all sorted now.

Interest has swirled around George Bello for years, spanning from his US youth national team career through his progression as an Atlanta United homegrown defender who's also with the USMNT.

The latest reports say that Premier League side Watford have made an inquiry on Bello, while over the summer Turkish clubs were linked with the left back who turns 20 in January.

"We've had quite a few inquiries about George Bello," technical director Carlos Bocanegra said on December 1. "Obviously he's a 19-year-old left-sided player that's very dynamic, very athletic, caps with the national team, 30-40 professional games under his belt. So you can imagine the type of interest that he's garnered. So, again, it'll be a tough decision for us in the offseason like quite a few of these other guys that we have."

It's safe to say Ezequiel Barco hasn't quite hit the exuberant expectations set when he joined Atlanta United in a league-record transfer four years ago, but the 22-year-old looks set to depart Atlanta for a non-insignificant fee this winter.

Barco has 17g/17a in 81 MLS appearances over the last four years and just wrapped up his best statistical campaign, with 7g/8a in 25 appearances. His talent suggests there's much more to come, but at his age, it'd be surprising to see a fifth season in MLS.

Part of that calculus and assumption is simple math: Atlanta are expected to sign Argentine youth international Thiago Almada for $16 million. They currently have three DPs and Barco is easily the likeliest to depart, rather than Josef Martinez or Luiz Araujo.

Almada's club, Velez Sarsfield, announced his transfer to Atlanta officially but ATLUTD put out a statement to clarify that they have an "exclusive option to sign" Almada from the Argentine Primera División.

A player who has regularly been linked with moves away from LAFC (and did indeed leave on loan to Spanish club Almeria last winter), Brian Rodriguez could be part of LAFC's rebuild.

Like Barco, Rodriguez hasn't quite lived up to the expectations that his pedigree and talent seemed to promise. He has 6g/9a in 41 MLS appearances, but is still a rising Uruguayan international with innate talent that should dictate a market. TBD here.

In an interview with Transfermarkt, Wagner said he wants to return to Europe this winter (though he said something similar last year and signed a new contract with the Philadelphia Union anyway).

Wagner, 24, has been among MLS' best left backs since debuting in 2019 after joining from German third-tier side Wurzburger Kickers. He's one to watch as the winter unfolds.

Justin Che impressed Bayern Munich on a training stint which earned a loan in 2021, ostensibly to be part of their U19 setup before he quickly was moved to Bayern's second team. When his loan expired in the summer, the Bundesliga giants were hopeful to arrange a permanent deal immediately.

With injuries and poor form thinning the defensive options last year, FC Dallas were intent to keep him in the summer when Bayern (and others) opened talks to try and sign him. The expectation is if the right offer arrives this winter, Dallas won't stand in Che's way. Bayern are among a few clubs involved for Che, including other Bundesliga sides and interest from the Premier League.

Che, 18, has a German passport. He made 12 starts for Dallas last season after returning from Germany.

Keep an eye on...

Among the very best defensive midfielders in MLS, Jose Martinez has plenty of clubs interested in securing his services. The tenacious No. 6 was yet another undervalued gem found by Philadelphia and has made 38 appearances over two seasons, integral to the new heights they reached by winning the Supporters' Shield in 2020 and making the Eastern Conference Final in 2021.

Martinez's stock rose at the Copa America, as his strong form with Venezuela boosted his profile at one of the biggest tournaments in the world. At 27 years old, the timing might be right.

Philly rejected offers in the summer for Martinez, per a source, as they intended to keep one of their most important players for the CCL and playoff run. Philly reached the semifinals of the CCL before losing to Club America and put up a valiant fight against NYCFC in the ECF despite missing 11 players due to health and safety protocols. It was a similar stance they took with Brenden Aaronson and Mark McKenzie, who were then transferred in the winter.

There will be more clubs circling for Martinez in January.

Another Venezuelan international, Casseres has spent four years with the Red Bulls and has steadily improved each year.

Casseres, who turns 22 in January, arrived in 2018 and spent the majority of his first season with RBNY II in the USL Championship. He broke into the first team in 2019 and only became more and more important over the years, delivering his best campaign this year, with 6g/4a in 27 appearances (24 starts). He started all four games for Venezuela at the Copa America.

He's ready for the next step, but as with all transfers, will the right opportunity and offer arrive?

Buksa had a huge 2021 for club and country, scoring 16 goals in 31 appearances (21 starts) for the record-setting Revs, while breaking into Poland's national team during World Cup qualifying and marking his performances with goals.

Reportedly the likes of Leicester City, AS Monaco and more are seriously interested in him, while Buksa himself has given interviews stating he wants a European return at some point, maybe even this winter. Let's see if the right offers/opportunities arrive. All quiet on this front so far.

The Revs acquired him for around $4 million ahead of the 2020 season. They are likely to double that investment – at least.

A number of big European clubs are interested in the USMNT goalkeeper, but New England's asking price is high. It being a World Cup year and such, if no club matches New England's valuation, perhaps a new contract would be a palatable outcome for all parties.

The Canadian and Toronto FC wonderkid may only have 439 minutes played in his MLS career, but the 17-year-old has long been on the radar of some of Europe's biggest clubs. With more than a few suitors, the market might dictate an early move.

Marshall-Rutty turns 18 in June, so if an interested club were so inclined to bid this winter and Toronto found the finances agreeable, a deal could be pre-arranged for when he turns 18.

The winger trained with Liverpool and Arsenal this offseason. Both clubs elevated him pretty quickly to the U-23 teams and there were even talks of Liverpool trying him at right back in training sessions.