Defending MLS champions LAFC battled to a hard-fought 1-1 draw with the Philadelphia Union in the first leg of their CONCACAF Champions League semifinal at Subaru Park on Wednesday night.

Daniel Gazdag netted a late penalty before Kellyn Acosta levelled the score in second-half stoppage time in a rematch of last year's MLS Cup championship game that LAFC won in dramatic fashion to secure its first league title.

The first half was a wide open affair that ended goalless and featured a heated exchange between both teams right before the break when Carlos Vela and Kai Wagner collided while sliding for the ball. Vela eventually got back on his feet and was able to carry on playing.

It was more end-to-end play in the second half -- but still without any goals -- with LAFC frontman Denis Bouanga forcing a save from Union keeper Andre Blake with his close-range shot from Jose Cifuentes' whipped in cross.

With the game looking likely to end in a draw, Acosta was whistled for handball in the 86th minute and Gazdag made no mistake from the penalty spot to put the Union in front.

But U.S. national teamer Acosta redeemed himself from the handball, scoring an unlikely equalizer with minutes remaining to give LAFC an away goal and a slight advantage in the tie after the opening leg.

LAFC hosts the decisive second leg at BMO Stadium on May 2 to determine who will play the winner of the other semifinal -- a Liga MX battle with Tigres leading Leon 2-1 after the first leg.

The Union are in the CCL semifinals for the second time, having fallen to Club America in the semis in 2021.

LAFC reached the 2020 final in their lone prior CCL appearance, losing 2-1 to Tigres.