The final regular season meeting of the year between the Portland Timbers and Seattle Sounders is the showpiece of the last MLS Rivalry Week of 2015. The game will kick off, after plenty of pre-game hullabaloo, just after 2 pm on Sunday afternoon.

For Seattle, this game is an absolute must-win. The Sounders, once the runaway leaders of the Western Conference, saw their season unravel over the summer. They are now in seventh place and on the outside looking in at the playoffs, and leading the league in losses, having won just one of their last seven, and two of their last 10. It's been an epic slide—one that started with a fractious and memorable US Open Cup lost to Portland in June. Finally getting healthy, in front of their biggest crowd of the season, the buck must stop here.

The Timbers are in a safer playoff position, and have more room for error, but Portland still hasn't convinced anyone that it's capable of contending for MLS Cup. The Timbers' saving grace this season has been that the team is undefeated when both Diego Chara and Will Johnson play, but thanks to a late red card picked up last Friday, Chara is suspended for this match. Johnson might be out as well.

So strap in. These games always mean plenty, but with the weather getting colder—it's supposed to rain in Seattle on Sunday—and opportunities dwindling, desperation is setting in as well.

The History

The story of Seattle's entire season comes back to that Open Cup meeting at Starfire just over two months ago, when Obafemi Martins got hurt, Clint Dempsey lost the few marbles he has, and the Sounders finished 3-1 losers with seven players on the field.

Nothing has been the same since then. The Timbers, along with half of the rest of MLS, capitalized on Seattle's period of self-destruction, pounding the Sounders 4-1 at Providence Park in late June. It was Portland's most euphoric game since they knocked Seattle out of the 2013 playoffs.

In the only pre-June meeting of the year between these two sides, and the only previous matchup at CenturyLink Field, the Timbers put in a solid performance just to be outdone by a late Clint Dempsey goal. That's traditionally been the story for Portland in Seattle—the Timbers have never won a regular season match at CenturyLink.

Thanks to what happened in the Cup, Portland could lose this game 10-0 and still have won the season series. But right now, all the pressure is piled on Seattle. The Timbers might not be that good, but even more so now that Chara is suspended, they have zero to lose. This is the hardest game to call of the year between these two sides. Anything could happen.

The Tactics

Otherwise known as, "Chara is banned, so what's the point anymore?"

The Timbers have been pretty much dreadful since April when either Will Johnson or Diego Chara doesn't play, and thanks to an idiotic red card in the dying seconds of the match against Houston, Chara is out for the next two matches.

The Columbian has a special commitment to getting banned for Seattle games. He missed this fixture last year too, as well as the Open Cup game this year for a red in the Open Cup game last year. Without Chara's speed, familiarity with Johnson, and defensive zeal, the Timbers could be in serious trouble.

Jack Jewsbury has been the backup central midfielder since George Fochive was yanked after 45 minutes against Orlando City in April, but Jewsbury's play has tailed off since the spring and Fochive has looked terrific in his time with T2. Both will be in the 18 on Sunday, and while I don't think Porter would be comfortable with the risk involved in opting for a rookie in Fochive over the ultimate veteran in Jewsbury, it might be the right call.

Or both might play. Caleb Porter said after practice on Friday that Johnson is dealing with leg soreness stemming from his leg break last year, and might not be able to start.

What we're unlikely to see is a formation change. While a 4-4-2 with Lucas Melano and Fanendo Adi up top might eventually be the Timbers' best look, it's not coming this weekend. Adi will be back in up top to occupy Chad Marshall, while Melano should play on the wing — but if Porter wants to come out and play defense (a common occurrence these days), Rodney Wallace could stay in.

Seattle has had plenty of injury problems for these last two months. Clint Dempsey and Osvaldo Alonso are massive game-time decisions, while Andreas Ivanschitz could be line for a debut if he passes fit. Nelson Valdes and Roman Torres, Seattle's two big summer signings, should start. Eric Friberg has been a good addition as well, while Martins will be in up top. If Alonso makes it, the lack of Chara will be felt even more keenly. Darlington Nagbe, for one, hopes Alonso can't go.

The Sounders took a B team to Honduras to play and lose to CD Olimpia in the Champions League midweek, so that game shouldn't have a huge impact here.

The Lineup

12 - Kwarasey
2 - Powell
24 - Ridgewell (C)
7 - Borchers
19 - Villafaña
13 - Jewsbury
5 - Fochive
6 - Nagbe
8 - Valeri
26 - Melano
9 - Adi

The Pick

It would surprise absolutely no one if these two clubs managed to find each other in a Wild Card playoff matchup, so this might very well not be the last chapter of this season's rivalry. But the Sounders have to win this game. If they don't, and fail to make the playoffs, Sigi Schmid might be out in November. It'd rate as one of the most historic collapses in league history. That's what Seattle is battling. Portland's central midfield problems are going to decide it. 2-1 Sounders.