Zlatan Ibrahimovic played his first full MLS game but he was unable to inspire his side as LA Galaxy lost 2-0 to Atlanta.
Keeper Brad Guzan frustrated LA to make it six games unbeaten for Atlanta, who are now one point behind Eastern Conference leaders New York City.
There were some flourishes - including a bicycle kick by Galaxy forward Ola Kamara early on that was big on ambition but lacking on accuracy.
Josef Martinez put the visitors ahead in the 22nd minute after the ball had rebounded once off the crossbar from an attempt by midfielder Julian Gressel then the right post as LA attempted to clear.
Galaxy failed to find an equaliser and Miguel Almiron's stoppage-time penalty secured Atlanta's victory.
Ibrahimovic told Spectrum SportsNet: "Today we didn't do well. Especially the first half was bad. Second we tried more. But when you chase the game it's a different game."
The Swedish former Manchester United striker, who was rumoured to be in line for a World Cup call-up, said he "felt good" after playing the full match.
However he added: "It doesn't matter if you lose how good you feel."
It was a better day for fellow Los Angeles side LAFC, whose inaugural season continued to show promise as they beat Montreal Impact 5-3.
Their second straight win saw four goals in the second half to cancel out a hat-trick by Impact's Ignacio Piatti.
It marked Montreal's third loss in a row.
FC Dallas maintained their unbeaten record so far this season with a 2-0 win over Philadelphia Union, who have not won in five games.
Mauro Diaz put Dallas ahead with a penalty in the 64th minute, while Maximiliano Urruti put the second away 10 minutes later.
Colorado Rapids played with 10 men for 70 minutes as Real Salt Lake left it late to claim a 3-0 victory.
Keeper Tim Howard was sent off for handling the ball outside the box, but Colorado held on until a handball by Tommy Smith gave Joao Plata the chance to score from the spot in the 82nd minute.
Damir Kreilach scored seven minutes later, followed by Albert Rusnak in injury time.
Defending champions Toronto FC suffered a punishing 5-1 defeat to Houston Dynamo, who enjoyed their first win in four matches.
Columbus Crew were held to a 2-2 draw by New England Revolution after Cristian Penilla levelled up in first-half stoppage time.
And the New York Red Bulls saw their 11-game unbeaten streak end in a 2-1 defeat to Chicago Fire.