The MLS play-offs have reached the conference finals stage, as four teams battle it out in the first legs on Sunday night - live on Sky Sports.
All four clubs are just two games away from reaching the MLS Cup final, when a new title winner will be crowned. With plenty on the line for all involved, we look at what to watch out for.
Columbus Crew v New York Red Bulls: Can the Red Bulls stop Columbus' aerial dominance?
It took a hard-fought effort from Columbus Crew to overcome Didier Drogba and Montreal Impact over the course of two legs in the MLS Eastern Conference semi-finals, but their hard work was rewarded as they defeated one of the league's most in-form sides, successfully reducing Drogba to few chances as he struggled to link play in the second leg.
Removing Drogba from dangerous positions was one way of succeeding, but Columbus' key players also stepped up a gear when they had the ball. Kei Kamara, who had 22 goals in the regular season, added another two while winger Ethan Finlay also got on the scoresheet.
The Red Bulls defeated a plucky DC United 2-0 on aggregate after Bradley Wright-Phillips sealed their conference final spot with a last-minute goal. New York's midfield have proved hard to battle, as shown in the second leg when trio Dax McCarty, Felipe and Sacha Kljestan flooded the central area to prevent DC from creating as Felipe (9) and McCarty (18) made 27 recoveries combined.
But the Red Bulls' defensive-minded players could be given a greater test in the first leg of the final and may wish to practice aerial duels. Kamara has scored 11 goals with his head in 2015, more than any other MLS player since 2010.
A lot of crosses from Finlay and Justin Meram will be expected, as Columbus have made 115 more crosses than any other team in the league this season. Head coach Jesse Marsch will surely want an intelligent display from his players should they wish to remain in the tie entering the second leg.
Portland Timbers v FC Dallas: Can Portland overcome a young Dallas side to reach their first-ever MLS Cup final?
Portland and FC Dallas have experienced high drama in the play-offs, with both being forced to have ties decided by the spot-kicks. Most recently, Dallas' tie with Seattle Sounders went beyond extra-time after the contest ended 2-1 (3-3 on aggregate).
The game in Frisco, Texas was 0-0 until the 84th minute before Tesho Akindele scored to make it 1-0 to Dallas. Towering centre back Chad Marshall thought he got the away goal winner for the Sounders in the 90th minute only for Dallas' own defender Walker Zimmerman to take the game to extra time, making the scoreline 2-1 deep into injury time.
Zimmerman performed more heroics as he struck the winner from the spot, but 20-year-old goalkeeper Jesse Gonzalez also drew plaudits for his two penalty saves. Zimmerman is only 22-years-old himself, and with Dallas' squad averaging the age of 24.5, head coach Oscar Pareja is proving with his class of 2015 you can win with kids.
For Portland, Fanendo Adi has been the star of their play-off run as his goal and assist helped the Timbers to a 2-0 away win against their Pacific Northwest rivals Vancouver Whitecaps. The Timbers now have the opportunity to make it to their first MLS Cup final.
Argentine number 10 Diego Valeri will be missing due to yellow card accumulation, but Portland will still be confident as they are unbeaten in all games they've led in this season.
However, FC Dallas have two of the most dangerous players in the league with South Americans Mauro Diaz and Fabio Castillo. Their pace and skill on the counter-attack may urge the Timbers to err on the side of caution, despite their home advantage, in this season-defining first leg.