Raptors forward Pascal Siakam controls the ball as Celtics center Robert Williams defends during their game Saturday in Toronto. Frank Gunn/The Canadian Press via the Associated Press

TORONTO — Grant Williams scored a career-high 25 points, Jaylen Brown had 27 and the Boston Celtics overcame the absence of leading scorer Jayson Tatum to extend their winning streak to nine games by beating the Toronto Raptors 106-104 on Saturday.

Already without Tatum, Boston’s injury woes worsened when guard Marcus Smart hurt his right ankle in the final minute of the first half and had to be helped to the locker room. He did not return.

Center Robert Williams stayed in the game after Brown collided with his left knee in the opening quarter. At halftime, though, Williams was ruled out for the second half because of a hyperextended knee.

“It says a lot about our team,” Boston Coach Joe Mazzulla said of the victory. “In the beginning of the game, you could obviously feel that we just didn’t have the juice. We just kept playing. We never wavered, we made great plays. Guys did a great job managing the game.”

Williams had left knee surgery last March but returned in the playoffs, but then had surgery again in September.

Mazzulla said Williams’ latest injury was “nothing serious,” and added that X-rays on Smart’s ankle revealed no structural damage.

Malcolm Brogdon scored 23 points and Payton Pritchard got all of his 12 points in the fourth quarter. The Celtics are unbeaten since a Jan. 3 defeat at Oklahoma City.

“To win in the NBA is hard enough, to win on the road down a bunch of guys is hard to do,” Brown said. “You don’t want to take it for granted, but we definitely have enough on this team, enough in this locker room, to win games whoever is on the floor.”

Al Horford scored only five points and shot 2 for 10, but he had a rebound, a blocked shot and a steal in the final 20 seconds.

“The box score doesn’t tell the story about what he does for us,” Mazzulla said. “When he takes it to another level defensively, we’re a different team.”

Grant Williams shot 7 for 13 and made 4 of 6 from 3-point range. He went 7 for 8 at the line.

“He was great tonight, man,” Mazzulla said. “He was the trigger for us.”

Pascal Siakam had 29 points and 10 assists, Gary Trent Jr. scored 22 points and Precious Achiuwa had 17 points and 11 rebounds in his first start of the season, but Toronto lost its third straight.

A potential NBA MVP candidate, Tatum sat because of a sore left wrist. He’s averaging 31.2 points, the third-highest total in the league, and a career-high 8.5 rebounds.

Tatum scored 51 points in Monday’s win over Charlotte, then had 34 points and a career-high 19 rebounds in Thursday’s overtime victory against Golden State, playing 48 of 53 minutes.

The Raptors were without guard Fred VanVleet, who was scratched shortly before tip-off because of soreness in his right ribs. Coach Nick Nurse said VanVleet is questionable for Sunday’s home game against the Knicks.

Toronto’s O.G. Anunoby left in the third quarter because of a sore right ankle. Anunoby was initially expected to return but did not play again. Anunoby scored 12 points before departing.

The Raptors attempted a season-low seven free throws.

“We just didn’t get anything at the free-throw line tonight,” Nurse said.

Trailing 85-81 through three quarters, the Celtics reclaimed the lead with a 9-0 run to begin the final quarter as Brown, Williams and Pritchard all made 3-pointers.

Trent missed a layup with 21 seconds left that would have tied it at 106. Toronto had one final chance after Boston was called for an offensive foul, but Horford forced a steal and Siakam turned it over at midcourt.

TIP-INS

Celtics: Derrick White started in Tatum’s place. … Brogdon and Luke Kornet started the second half. … Boston has won 13 of 15.

Raptors: Attempted a season-low seven free throws. … Siakam missed four of his first five field goal attempts, then made 12 of the next 15. He finished with nine rebounds. … Barnes scored 10 points but didn’t score in the second half.