Golden State, adjusting to life without injured Kevin Durant, fell to the Chicago Bulls on Thursday, just the second time in nearly two years the Warriors have suffered back-to-back NBA regular-season defeats.
Jimmy Butler scored 22 points to lead four Bulls players in double-figures in the 94-87 triumph.
The Warriors' points total was their season low, and they lost a second straight regular-season contest for the first time since April of 2015.
The Warriors had fallen 112-108 to the Washington Wizards on Tuesday, when Durant limped out of the game in the first quarter with what was later diagnosed as a left knee ligament sprain and bone bruise.
The former NBA Most Valuable Player will be sidelined indefinitely, although the Warriors, who have already secured a playoff berth, haven't ruled out a return before the end of the regular season.
"Obviously, you feel for him and want him to get healthy as fast as possible but not rush it because we have a long journey ahead of us going into the playoffs," two-time NBA MVP Stephen Curry said. "Next man up mentality, but obviously it will be tough to replace a guy like KD."
Curry led the Warriors with 23 points, but he and "Splash Brother" teammate Klay Thompson combined to make just three of 22 three-point attempts.
Overall, the Warriors were six-for-30 from three-point range in the defeat. Thompson added 13 points and Draymond Green contributed a dozen in the defeat.
The Warriors had led 51-47 at halftime, and erased a five-point deficit with 9:09 to play thanks to three baskets from Curry and a driving layup from David West that gave Golden State an 85-84 lead with 5:43 to go.
But Golden State couldn't maintain the momentum.
Veteran Dwyane Wade scored 12 points for Chicago, putting the Bulls up 88-85 with 2:16 remaining.
Bulls reserve Paul Zipser closed out a 7-0 scoring run with three-pointer that stretched Chicago's lead to six points with 1:41 to play.
With the Warriors struggling from the floor, Chicago closed out the victory with a series of free-throws.
The Bulls won for the fifth time in six games improving to 31-30 -- sixth in the Eastern Conference.
The Warriors slipped to 50-11 -- still the best record in the league.