Patrick Vieira oversaw a thrilling 4-3 victory at Chicago Fire in his first Major League Soccer match as New York City FC coach.

Vieira swapped parent club Manchester City for New York in the off-season, replacing Jason Kreis after the club missed the play-offs last term despite boasting David Villa, Andrea Pirlo and Frank Lampard.

The former France international's reign got off to the perfect start in the season opener on Monday (AEDT), thanks to a three-goal first half at Toyota Park in Chicago.

Playing in the absence of an underdone Lampard, New York City opened the scoring in the 10th minute when midfielder Thomas McNamara curled a shot in off the post.

Fire responded through Razvan Cocis nine minutes later, but New York City forward Tony Taylor restored the visitors' lead just shy of the half-hour mark before Khiry Shelton made it 3-1 in the 36th minute.

Kennedy Igboananike reduced the deficit four minutes into the second half, only for Mikkel Diskerud to re-establish New York's two-goal buffer after 63 minutes.

Fire converted a 72nd-minute penalty via David Accam but New York held on in the Eastern Conference.

Star-studded LA Galaxy rallied to thrash DC United 4-1 as Ashley Cole and Nigel de Jong took their MLS bows.

Galaxy trailed to a fifth-minute opener from Lamar Neagle before the home side piled on four unanswered goals in the second half.

MLS debutant Daniel Steres levelled proceedings in the 54th minute and substitute Mike Magee gave the Galaxy a 2-1 lead 10 minutes later.

Galaxy ensured victory courtesy of goals from captain Robbie Keane — a penalty won by Magee — and Magee got his head on to a free-kick in the final seven minutes of regulation time to seal the deal.

Last season's Supporters' Shield winner New York Red Bulls was accounted for 2-0 by Toronto FC.

Reigning MVP Sebastian Giovinco broke the deadlock from the spot with eight minutes remaining and Marco Delgado sealed the points in the 90th minute.

Defending champion Portland Timbers continued where it left off after a 2-1 win at home to Columbus Crew.

In a rematch of the 2015 MLS Cup final, the Timbers reigned supreme after Diego Valeri and Fanendo Adi scored either side of Federico Higuain's 68th-minute overhead kick.

A pair of stoppage-time goals from Cyle Larin and Adrian Winter salvaged a dramatic 2-2 draw for Orlando City — missing Kaka — against visiting Real Salt Lake as both teams were reduced to 10 men in the first half.

In other results, Ignacio Piatti's brace inspired Montreal Impact to a 3-2 win at Vancouver Whitecaps in the absence of Didier Drogba.

San Jose Earthquakes and Sporting Kansas City were 1-0 winners over Colorado Rapids and Seattle Sounders respectively.

Daigo Kobayashi scored in the 90th minute as New England Revolution claimed a 3-3 draw at Houston Dynamo, while FC Dallas beat Philadelphia Union 2-0.