TORONTO -- An initial exam of Philadelphia 76ers superstar Joel Embiid's sprained right thumb suggested ligament damage, sources told ESPN's Ramona Shelburne and Adrian Wojnarowski, though an MRI still is needed to learn the extent of the injury.

"We feel like it's not a great injury," Rivers said before the 76ers faced the Toronto Raptors in Game 4 of their Eastern Conference first-round playoff series at Scotiabank Arena on Saturday afternoon.

Sources told Shelburne and Wojnarowski on Friday that Embiid was feeling significant pain and discomfort in the thumb and that he could get an MRI in the near future to determine whether there is ligament damage.

Rivers said he expects Embiid to get the MRI after the team returns to Philadelphia after Saturday's game.

"Yeah, I mean, I guess we're gonna do the MRI," Rivers said. "I think we already know what it is, to be honest, but we just got to make sure. There's no really additional treatment to that, though."

Rivers also said he believes Embiid can't injure the thumb further by playing.

"Yeah, there's concern," he said. "But, you know, it is what it is. The one thing we know [is] it can't get worse."

Embiid came out for his usual pregame shooting routine about 45 minutes before tipoff. He was shooting with a wrap on the thumb and doing some dribbling with his right hand -- though often catching passes with his left.

Embiid appeared to suffer the injury, which the team is calling a right thumb sprain, in the first half of Philadelphia's 104-101 victory over Toronto in Game 3, in which Embiid hit the game-winning 3-pointer with less than a second to go. He had 28 of his 33 points in the second half and overtime to help drag the 76ers back from a 17-point first-half deficit.

He arrived at his postgame press conference nearly two hours after the game had ended. He was wearing a brace on his right (shooting) hand and with his right thumb taped.

"I don't exactly know what happened," Embiid said after Wednesday's victory. "But I just started feeling pain and think I might have twisted it. So we're gonna see what's going on [Thursday]."

When asked if the injury could possibly impact his availability for Game 4, Embiid said, "No. No chance."

Embiid was in good spirits at practice Friday, when he again had the brace on his right hand.

Toronto, meanwhile, got back standout rookie forward Scottie Barnes, who missed the past two games with a sprained left ankle he suffered in the fourth quarter of Game 1.

Barnes, who was honored with the Rookie of the Year Award before today's game, had been listed as doubtful.

Barnes took the court for a short workout for a few minutes before heading into the locker room. Raptors coach Nick Nurse said that Barnes, who had 15 points, 10 rebounds and 8 assists in Game 1 before getting hurt, would likely get as much time on the court as he could handle if he's cleared to play.

"If they clear him, I would imagine that he's gonna be OK," Nurse said. "It wasn't too serious ... so if they clear them out, I'd imagine he'll go out there and play.

"I mean, obviously he's gonna have to try it. If they clear him and he tries it and doesn't feel quite right then he'll be done for the night. But if he feels OK and you know, adrenaline gets pumping and he gets loose and gets out there, then we'll give him a good long run, as much as he can handle."

If Philadelphia is able to close out the series Saturday, it will be the first time the team has swept a playoff series since 1991, and the first time it will have swept a four-game playoff series since 1985 -- when Charles Barkley, Julius Erving and Moses Malone were teammates.