MLS Supporters' Shield leaders Los Angeles FC defeated Portland Timbers 3-2, while defending champions Atlanta United won thanks to Josef Martinez.
High-flying LAFC crashed the re-opening of Portland's Providence Park on Saturday – star Carlos Vela scoring again to lead the visitors.
Vela broke the deadlock with his league-leading 16th goal of the campaign after the former Arsenal and Real Sociedad forward slotted in the sixth-minute opener.
Diego Rossi made it 2-0 for LAFC in the 34th minute before Cristhian Paredes reduced the Timbers' deficit within a minute of the second half.
However, Latif Blessing restored LAFC's two-goal advantage eight minutes later, with Brian Fernandez's late bicycle kick proving a consolation.
Unbeaten in eight games and with just one defeat all season, LAFC are nine points clear of city rivals LA Galaxy in the Western Conference.
Martinez, meanwhile, was the hero as Atlanta accounted for Chicago Fire 2-0 on home soil at Mercedes-Benz Stadium.
The Venezuela international recorded his second consecutive brace to lead Atlanta to back-to-back victories.
Martinez, who has five goals in his past three games, scored twice in the first half as Atlanta moved within a point of Eastern Conference leaders DC United.
Wayne Rooney's DC were held to a 1-1 draw by San Jose Earthquakes, who were again aided by record goalscorer Chris Wondolowski.
In other results, Nani scored in Orlando City's 3-0 win at Montreal Impact, New York Red Bulls routed Real Salt Lake 4-0, Colorado Rapids beat FC Cincinnati 3-1, Houston Dynamo drew 1-1 with Sporting Kansas City, Dallas edged Seattle Sounders 2-1 and New York City earned a 2-2 draw against Columbus Crew.