Mason Toye scored twice as Minnesota United shocked league-leading Los Angeles FC 2-0, while Zlatan Ibrahimovic was unable to prevent LA Galaxy from losing late at Seattle Sounders.
Toye's first-half brace saw Western Conference and Supporters' Shield leaders LAFC surprisingly beaten at home for the first time this MLS season on Sunday.
LAFC had gone 13 league matches unbeaten at Banc of California Stadium in 2019 but that streak came to an end in the absence of star Carlos Vela, who missed the match after suffering a hamstring injury against the Galaxy last time out.
Toye stole the show for visiting Minnesota, who silenced the Los Angeles crowd in the 25th minute when the forward found the back of the net from an acute angle.
He doubled the lead just four minutes later after producing a stunning long-range strike to beat LAFC goalkeeper Pablo Sisniega.
Minnesota moved up to third in the Western Conference, 17 points adrift of high-flying LAFC after 28 matches, and a point behind second-placed Seattle.
The Sounders consolidated their place in the standings thanks to Sunday's thrilling 4-3 victory at home to Ibrahimovic's Galaxy.
Trailing 2-0 after 55 minutes, Ibrahimovic's goal in the 66th minute triggered a comeback as the Galaxy equalised through Uriel Antuna with 15 minutes remaining.
Seattle quickly restored their lead via Jordan Morris two minutes later, only for Jorgen Skjelvik to make it 3-3 in the 81st minute.
But the Sounders had the final say in a wild showdown as Cristian Roldan – who gave Seattle a 2-0 lead – netted his second of the match at the death.