Carlos Vela scored two goals in the first half and set up Diego Rossi's tiebreaking goal in the second half, and LAFC advanced to the MLS Western Conference final with a wild 5-3 victory over the LA Galaxy on Thursday night in the first postseason edition of this city rivalry.

Adama Diomande added two goals in the second half as top-seeded LAFC earned the 2-year-old franchise's first postseason victory.

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LAFC also beat the Galaxy for the first time in the sixth chapter of the lively crosstown derby dubbed El Trafico.

Zlatan Ibrahimovic had a goal and an assist in perhaps his final game for the Galaxy, while both teams put on a dazzling offensive show in front of a raucous sellout crowd near downtown Los Angeles.

LAFC advanced to face the Seattle Sounders in the Western Conference final on Tuesday night (watch on ESPN, 10 p.m. ET) at Banc of California Stadium. The winner faces Toronto FC or Atlanta United for the MLS Cup on Nov. 10.

After Vela staked LAFC to an early lead with a dominant performance befitting the forward who just set the MLS single-season record with 34 goals, Diomande scored twice as a second-half substitute in his first game in a month.

LAFC needed all that offense to hold off Ibrahimovic. The 38-year-old Swedish superstar set up Cristian Pavon's goal and then drilled home a tying goal early in the second half, his ninth against LAFC in less than two MLS seasons.

Galaxy star Romain Alessandrini then set up a header by Rolf Feltscher in the 77th minute to trim LAFC's lead to 4-3, but Diomande rampaged downfield to chip home the clinching goal in the 80th minute.

LAFC posted the best regular season in MLS history in just its second year of existence, reaching the league records for points, goals and goal differential. But LAFC needed this win to shake free of the shadow cast by the five-time champion Galaxy, who were 2-0-3 against LAFC.

The Galaxy were revitalized this season by the arrival of coach Guillermo Barros Schelotto and Argentine star Pavon, returning to the playoffs after a two-year absence behind the imperious Ibrahimovic, who scored 30 goals.

After setting an MLS record with 34 goals in his spectacular regular season, Vela opened the postseason with his first career MLS playoff goal. The Mexican star has scored in all six editions of El Tráfico.