Seattle is trying to make MLS history. Los Angeles would love nothing more than to send Landon Donovan into retirement raising another trophy.

New England is the hottest team in the league entering the playoffs after the addition of midfielder Jermaine Jones. And New York's Bradley Wright-Phillips gets two more games to try to add to his scoring barrage while questions linger about whether this will be Thierry Henry's farewell to the MLS.

The MLS Cup playoffs get started in earnest this weekend with the first of the two-leg, aggregate-score conference semifinals. Seattle enters as the favorite after winning the Supporters' Shield as the best team in the league during the regular season. But only twice in the past decade has the Supporters' Shield winner gone on to win the MLS Cup title.

New this year to the MLS postseason is the introduction of away goals as a deciding factor. That tiebreaker has been a staple of the Champions League in Europe but has only been introduced into the MLS playoff structure.

"It rewards you for playing on the road and not just sitting back and trying to get a 0-0 result on the road and coming home. So you think about it a little bit more," Seattle coach Sigi Schmid said.

Here are the conference semifinal matchups:

WESTERN CONFERENCE

SEATTLE SOUNDERS vs. FC DALLAS

Seattle is trying to become the first team to win the U.S. Open Cup, Supporters' Shield and MLS Cup title in the same season. The Sounders were the first club since ties were introduced to finish the regular season with 20 victories. Getting to an MLS Cup title match would be the final step for Seattle. Seattle has advanced to the Western Conference finals only once in its five previous playoff trips. Seattle went 2-1 in the regular season against Dallas, including an important 3-2 comeback win on the road early. The Sounders beat Dallas 2-1 in Seattle in May, but dropped their last trip to Texas in September when David Texiera scored twice and an 88th-minute goal by Blas Perez capped the 3-1 win.

LOS ANGELES GALAXY vs. REAL SALT LAKE

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Seattle, LA favorites as MLS playoffs get going