Obed Vargas' breakout rookie campaign has been put on hold, as Seattle Sounders FC head coach Brian Schmetzer confirmed Thursday that the 16-year-old homegrown midfielder has suffered a stress fracture in his lower back.

Schmetzer said the injury will keep Vargas out of action for "multiple weeks", which also means he can't join the United States at the ongoing Concacaf U-20 Championship, a tournament that involves pursuing 2023 FIFA U-20 World Cup and 2024 Olympics spots. Vargas was initially slated to meet the U-20s after the group stage, but will now be replaced by D.C. United homegrown midfielder Jackson Hopkins.

Vargas had emerged as one of the stories in the first half of Seattle's 2022 campaign, making 13 appearances and 10 starts in MLS play while also seeing significant minutes during the club's victorious Concacaf Champions League run. He's remained a regular fixture in Seattle's starting XI after Designated Player teammate João Paulo tore his ACL in the CCL Final.

"[Vargas] will be out seeing a back specialist every couple of weeks, but this is going to need time to heal," Schmetzer said. "So, it's really unfortunate because the kid was playing well for us and also had a chance to be with the U-20s. So it's tough. But the fact of the matter is, we've got a deep team."

With Vargas out, Seattle's depth will be tested. They have a pair of additional homegrowns with MLS experience at the position in Josh Atencio and Danny Leyva, and veteran utility man Kelyn Rowe is capable of covering there. Seattle captain Nicolas Lodeiro and US international Cristian Roldan are also candidates that could drop back from their spots in the attacking midfield.

"[Vargas] covered for JP, we've got Josh coming back, Danny, Kelyn can fit in there," Schmetzer said. "So the team will be fine, but it's just a bummer for the kid because the kid was looking pretty good. ... We'll figure something out. We've got three games next week, so chances are all three of those players are going to play.

" ... Again, we've got three games this week. We'll see how those go, we'll certainly make changes as necessary. But for the long term, we've been thinking about as a coaching staff: What is the best version of this team? Because JP's injury was significant. So we've got to figure out a way, how we solve that whole thing. Now we've got another injury, so we're working on it."

Seattle return to action Saturday when hosting Sporting Kansas City in MLS Week 16 (3 pm ET | ABC, ESPN Deportes). They've risen to seventh in the Western Conference standings after a slow start.