Looney suffered the injury late in the first half of Tuesday's 111-107 loss to the Boston Celtics and had an MRI late Tuesday night that confirmed the sprain. He will be reevaluated in two weeks as he continues rehab.
"This was a fluke," Warriors coach Steve Kerr said after the game. "He caught his foot on the floor and rolled the ankle. Just the way it goes. I feel bad for him because he's worked so hard to get back to this space and he's really been playing well for us, so it's a big blow."
Looney's injury comes at a bad time for the 11-10 Warriors. They are already playing without rookie center James Wiseman, who sprained his left wrist in last Saturday's win over the Detroit Pistons and will be reevaluated in a week. Backup big man Marquese Chriss has been out since the first week of the season after suffering a serious ankle injury during a practice in Chicago. It remains unclear if he will return this season.
"Eric Paschall becomes a bigger part of what we're doing and so does Juan," Kerr said. "I guess Juan sort of qualifies as a big man, kind of. Eric definitely does. So we'll be short-handed. Draymond will play a lot of 5 and Eric will get more minutes, and we'll see what happens from there."
Warriors star guard Stephen Curry is hopeful that the Warriors can use the small-ball lineup to their advantage as they get set for a four-game road swing to Dallas and San Antonio over the next week.
"You kind of have to flip it on its head," Curry said after Tuesday's loss. "Everybody's going to talk about what we can't do with a small-ball lineup, but we can focus on what we can do and that's play fast, get everybody involved, ball can be moving. Create chaos on both ends of the floor and then figure out how you rebound and how you [shore] up the paint on the defensive end. So with Dallas and San Antonio, it will be interesting because they do -- [Kristaps] Porzingis is huge, but they do play a lot of small ball, too, so maybe that will match up well for us."