Not even a double-double from Russell Westbrook could prevent the Thunder from going down 104-88 to the Pistons on Tuesday.
The Los Angeles Clippers were too good for the Brooklyn Nets, winning 127-95.
Kawhi Leonard’s double-double inspired the San Antonio Spurs to a 94-90 victory against the Miami Heat.
A week ago, the Thunder were 6-1 and flying high but Oklahoma City are now licking their wounds following a fourth consecutive defeat.
Westbrook put up 33 points, 15 rebounds and eight assists, but he had no support. Jerami Grant (11) and Enes Kanter (10) were the only other players with double-digit points.
The Pistons were led by Tobias Harris (22 points), Aron Baynes (20 points) in the absence of star Andre Drummond.
After suffering back-to-back defeats last week, the Spurs are winning again.
Leonard’s 24 points and 12 rebounds helped the Spurs extinguish the Heat in San Antonio.
Heat pair Hassan Whiteside (23 points, 17 rebounds) and Dion Waiters (27 points) combined for 50 points but it was not enough.
James Harden’s 33 points led the Houston Rockets past the Philadelphia 76ers 115-88.
The New Orleans Pelicans upstaged the Boston Celtics 106-105, the New York Knicks were 93-77 winners over the Dallas Mavericks, the Orlando Magic lost 88-69 to the Indiana Pacers, while the Memphis Grizzlies trumped the Utah Jazz 102-96.
After clashing last month, reigning champions the Cleveland Cavaliers and Eastern Conference rivals the Toronto Raptors clash on Wednesday. Among the other games, the Atlanta Hawks face the Heat, while the Portland Trail Blazers take on the Chicago Bulls.