Warriors coach Steve Kerr updated the injury list Tuesday ahead of the matchup at Oracle Arena, which comes with the best-of-seven title showdown against Toronto deadlocked 1-1.
The Warriors seek a third consecutive NBA crown and their fourth in five seasons while the Raptors are in the finals for the first time in their 24-season history.
Thompson, averaging 19.5 points in the playoffs, is listed as day-to-day for game three after an MRI exam Monday showed him with a mild left hamstring strain.
Thompson left Golden State's 109-104 victory Sunday at Toronto with 7:59 to play with hamstring tightness.
"He says he's feeling well and a lot better than yesterday and thinks he'll be ready to go," Kerr said.
"What we'll have to determine is if that's a risk. If there's a risk we'd rather you have the next couple days."
Durant, this year's top playoff scorer for Golden State with 34.2 points a game and Most Valuable Player in the past two NBA Finals, has been out for nearly a month with a right calf injury.
Kerr has said the superstar forward must take part in a practice before playing and that while he missed Tuesday's workout he would take the court at the team's training facility.
"Kevin is going to get on the floor at the practice facility later," Kerr said. "He's out for tomorrow but improving.
"Kevin won't play tomorrow. He's ramping up his exercise routines and workouts."
Warriors reserve forward Looney, averging 7.2 points and 4.6 rebounds in the playoffs, is done for the finals after an MRI Monday showed Looney with a fracture of the cartilage connecting the right ribs to the sternum.
"Looney is out for the series," Kerr said. "It's not going to be anything bad long term. But it's going to keep him out the rest of the series. Fortunately it won't affect him in the future but it's a big loss for us."