Decision Day: Here's everything you need to know before Sunday

It’s called #DecisionDay for a reason. 

There are still four spots in the Audi 2015 MLS Cup Playoffs that remain unclaimed heading into the final day of the regular season. But there’s also plenty more at stake, especially when it comes to playoff seeding.

Here’s the complete list of what's on the line so you can keep tabs on Sunday:

Who gets the final four tickets to the Audi 2015 MLS Cup Playoffs?

There’s only one spot left in the Eastern Conference and two teams vying for it. Orlando City (44pts) need to win big at the Philadelphia Union and hope that the New England Revolution (47pts) lose big vs. New York City FC, because even if the Lions catch the Revs in the standings on 47pts, the goal differential tiebreaker would be needed. Orlando enter #DecisionDay with a significantly worse goal differential (-9) than the Revs (-1). 

In the Western Conference, there are four teams battling for three slots. Portland (50pts) look like a cinch for one of them, while Seattle (48pts) and Sporting Kansas City (48pts) will want to make sure they don’t slip up and give the San Jose Earthquakes (47pts) a chance to overtake them.

Who will get the last two Knockout Round byes? 

The New York Red Bulls (No. 1 seed in East) and FC Dallas (No. 1 seed in West) already know they’ve avoided the midweek, single-elimination Knockout Round matches on Wednesday, Oct. 28 and Thursday, Oct. 29. But the No. 2 seed in each conference also gets a bye.

In the East, the winner of the match between Columbus Crew SC (50pts) and D.C. United (51pts) at MAPFRE Stadium (5 pm ET, FS1 and FOX Deportes) will clinch the East’s bye, but if they tie, Toronto FC still have a chance to snag it. 

Meanwhile, in the West, the defending MLS Cup champions LA Galaxy (51pts) will hope they can survive a trip to Sporting Park (7 pm ET, ESPN, ESPN3 and ESPN Deportes) and hang on to the No. 2 seed. Any misstep by Bruce Arena’s side, and the Portland Timbers (vs. already-eliminated Colorado) and the Vancouver Whitecaps (50pts, vs. already-eliminated Houston) will look to take advantage.

Who gets to host the Knockout Round matches? 

If you can’t get that Knockout Round bye, the next best thing is hosting the winner-take-all match.

Why is this important? Well, of the eight single-elimination Knockout Round matches played in MLS history since 2011, home teams have won six.

So if you thought the chase for the No. 2 seed is going to be a mad scramble, the No. 3 and No 4 seeds promise to be in flux for most of #DecisionDay

Who wins the Supporters’ Shield?

The Supporters' Shield, awarded to the best regular-season team in MLS, will belong to the New York Red Bulls or FC Dallas, who both have 57 points and 17 wins. If the teams earn the same results in their final matches, the regular-season titlist will be determined by goal differential tiebreaker; the Red Bulls currently have the edge going into #DecisionDay (+18 vs. +12 for FC Dallas).

Will Giovinco take the Audi Golden Boot outright?

Barring a goal-scoring binge by LA’s Robbie Keane (19 goals) in KC, Toronto FC superstar Sebastian Giovinco (22 goals) looks set to claim the Audi Golden Boot awarded to the top scorer in MLS. 

Crew SC forward Kei Kamara is actually tied with Giovinco on 22 goals, but Kamara is suspended for the final match, and Giovinco holds the assists tiebreaker (15 assists to Kamara's 8).

Of course, if Giovinco gets on the scoresheet himself, he can claim the title the old-fashioned way.