An MRI on Thompson confirmed he suffered a "mild" strained hamstring in Golden State's 109-104 Game 2 victory Sunday.
The Warriors will be without Kevon Looney. The team noted Looney will be out indefinitely after he suffered a non-displaced first costal cartilage fracture.
Kevin Durant's availability is unclear as well. Yahoo Sports' Chris Haynes reported Friday the Warriors were hopeful he'd return from a strained calf in time for Game 3 but that Game 4 on Friday was the more realistic possibility.
Even when Golden State is at full strength, Thompson is a key member of the starting lineup. But as injuries pile up, the veteran 2-guard's role grows.
He's averaging 19.5 points per game and shooting 41.1 percent from beyond the arc in the postseason. In addition to the value he brings on offense, Thompson's perimeter defense is pivotal in keeping Kawhi Leonard somewhat in check.
If Thompson is questionable, then there's a chance he will suit up for Golden State in Game 3.
Should the Warriors be without Thompson—and Durant too—the Raptors will have a great chance to steal a win at Oracle Arena and go ahead 2-1 in the series.