An 81st-minute goal from Jahmir Hyka saw the San Jose Earthquakes to a 1-0 win which marked Dallas' first defeat.
Hyka's goal was a stunner as he jumped to take a touch over a defender before calmly placing a finish in off the post.
Dallas' loss – the first Oscar Pareja's men have suffered through 10 games – left them third in a Western Conference which saw its top three teams beaten.
Second-placed Houston was no match for Miguel Almiron and Atlanta United, who recorded a 4-1 win.
Almiron opened the scoring for the home side on the half-hour mark, taking a touch before unleashing a powerful left-footed effort past Joe Willis.
He doubled his and his team's tally before halftime, skipping into the area before making it 2-0.
Julian Gressel extended the lead in scrappy fashion before Almiron completed his hat-trick from the penalty spot.
Erick Torres scored a late penalty for Houston, whose second straight loss left the club second in the table.
The Chicago Fire continued their climb up the Eastern Conference table, extending their winning streak to three and moving into second after a 1-0 success against DC United.