The Warriors waited to make a final decision on Curry's status until he tried to warm up. He cut his extensive pregame routine short after about five minutes, appearing to be in discomfort, and left the court shaking his head.
He took the court some 90 minutes before tipoff and went through his normal dribbling session before he started shooting. He put little pressure on his tender right ankle while taking several shots and hit six 3-pointers in the corner.
At one point, Curry lined up to shoot a long jumper from the right wing but didn't release the ball and hopped in apparent discomfort before throwing the ball in the air. He left the court at Oracle Arena moments later.
Curry, team physicians, Warriors owner Joe Lacob and Warriors general manager Bob Myers met in the training room after Curry's exit. Lacob said Curry did not aggravate the ankle but simply wasn't healthy enough to play.
Coach Steve Kerr said earlier in the day that he and Curry had a long chat.
"We will definitely err on the side of caution," Kerr said. "If he's not right, then he's not going to play. It's not worth risking turning this into a long-term issue."
"We had a good conversation before shootaround, and Steph is a very rational person. He's easy to speak with, and we kind of went over the different scenarios. He understands we have, first of all, his best interests at heart -- his career. We know that he had surgery on that ankle four years ago. He has a lot of basketball ahead of him. There's plenty of cases in the past where people played through stuff, and it didn't turn out so well -- Grant Hill being the one that always jumps out at me -- and whether that's the same type of thing as this, I don't really know. But I do know that we have to look after his health because the competitor that he is, he's going to want to play."
Curry injured his right ankle when he missed a shot and twisted the ankle as he turned to get back on defense late in the first half of Golden State's 104-78 win over Houston on Saturday in the series opener. Curry tried to come back in the second half before quickly being pulled by coach Steve Kerr, who noticed Curry wasn't right.
In the 20 minutes Curry played in Game 1, the Warriors outscored the Rockets by 28. In the 28 minutes he sat, they were outscored by two.
"There's a smaller margin for error," Kerr said of the Warriors playing without their superstar point guard.
Curry didn't take part in practice Sunday or morning shootaround Monday. He received treatment instead. He now has until Thursday night's Game 3 in Houston to try to get healthy.
Golden State beat the Rockets without Curry once this season, in a 114-110 win Dec. 31 in Houston. Klay Thompson picked up much of the scoring load with 38 points that game, and Andre Iguodala added 20.
Thompson said it will take more than just him to replace Curry's league-leading 30.1 points per game and everything else he offers.
"Obviously, 30 points out of the lineup, a lot of playmaking, a lot of easy buckets," Thompson said Monday before Curry was ruled out. "We just have to do it in a more meticulous way, as far as moving the ball, being more patient. Without Steph in the lineup, we don't have those easy looks in transition he usually gives us. We just got to do it even more as a team now and rely heavily on our defense and get out on transition."
Shaun Livingston moved into the starting lineup in Curry's place. Livingston, who left Sunday's practice with an illness, averaged 6.3 points and 3.0 assists per game this season.
"I think their small lineup is still unconventional," interim Rockets coach J.B. Bickerstaff said. "They still have guys that can shoot it and can score and guys that move well without the ball. I think their system doesn't change. They'll still play the same way. They'll push it at you. They'll still shoot a ton of 3s. They'll continue to move. So you have to be prepared for that."
ESPN's Ethan Sherwood Strauss and The Associated Press contributed to this report.