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, have not 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.
- 'Part of the game' -
But Golden State couldn't maintain the momentum.
"A couple of shots we normally make did not fall," said Curry, who was 10 of 27 from the field. "That's not the reason we lost."
Warriors coach Steve Kerr said his team didn't play with enough urgency to make up for their cold shooting.
"You are not always going to shoot well," Kerr said. "When that happens, the ball is gold. You have to value each possession. Our intensity and focus was not there."
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.
"Our defense hasn't been good of late," Wade said. "I thought today, our attention to detail was phenomenal. They missed some shots -- even some of them open. But that's part of the game."
The Warriors slipped to 50-11 -- still the best record in the league.
Elsewhere, Damian Lillard scored 33 points as the Portland Trail Blazers used a 16-0 surge late in the game to defeat the Oklahoma City Thunder 114-109 at Moda Center.
Lillard led a half dozen Blazers in double figures as the Portland improved to 25-35 on the season and won for only the third time in 10 games. Jusuf Nurkic tallied 18 points, 12 rebounds and six assists for the Blazers.
Russell Westbrook scored 45 points for Oklahoma City but made only 12 of 36 shots from the field. He added eight rebounds and four assists.
Enes Kanter came off the bench for 18 points and 10 rebounds for the Thunder, who saw their four-game winning streak end.
Westbrook scored 28 first-half points, and Oklahoma City closed on a 12-0 run in the final 1:17 to take a 60-57 lead at halftime.