BOSTON -- Donovan Mitchell banked in a 3-pointer from a few steps beyond the top of the arc and could only shrug as he backpedaled back on defense. He followed with two baskets in the lane to give the Cleveland Cavaliers a 16-point lead.

"Sometimes you get lucky," Mitchell said after scoring 29 points to help Cleveland beat Boston 118-94 on Thursday night. "Shooters shoot."

Two nights after losing the opener by 25 points, the Cavaliers answered with a blowout of their own, beating the top-seeded Celtics in Boston to tie their Eastern Conference semifinal series at one game apiece. The teams now head to Cleveland for Games 3 and 4 on Saturday and Monday.

"We expected them to play better and they did," Celtics center Al Horford said. "They responded and we didn't."

Mitchell scored 33 points in the opener but got little help. On Thursday, the Cavs All-Star took just six shots and scored six points in the first half, while handing out five assists. Mitchell had 16 points in the third quarter and hit three straight baskets to start the fourth, including the 28-footer off the glass.

"I hadn't shot much, trying to find ways to get guys involved early, and picking my spots. I was just continuing to find ways to apply pressure on them," said Mitchell, who finished with eight assists and seven rebounds.

"In the second half it was scoring," he said. "Sometimes it's assists. Sometimes it's rebounds. Whatever it takes. And when it was time to go, it's time to go. I knew at some point I was going to have to start, obviously, shooting."

Jayson Tatum scored 25 for Boston, and Jaylen Brown added 19 points. But Derrick White, whose 25 points in Game 1 helped the Celtics coast to a 120-95 win, managed just 10 points, missing seven of his eight 3-point tries.

With the win, the Cavaliers assured themselves of at least a fifth game back in Boston on Wednesday. And after finally getting their first road win in this postseason, they showed that they can win there.

"When we defend the way we defended and our shots fall, what we do travels," Cleveland coach J.B. Bickerstaff said. "And we can win anywhere."

Evan Mobley had 21 points and 10 rebounds for his third straight double-double, and his fifth of this postseason. Caris LeVert scored 21 off the bench for Cleveland, hitting a pull-up jumper midway through the fourth quarter that gave the Cavaliers a 20-point lead and started a parade of fans to the exits. Many of those who stayed began booing.

A minute later, after the Celtics missed another 3-pointer - they were 8 for 35 from long distance in all -- LeVert made a layup and drew a flagrant foul from Tatum. It was a 25-point game, and Boston coach Joe Mazzulla emptied his bench.

Bickerstaff followed soon after, getting some rest for Mitchell, who played a game-high 37 minutes on Tuesday night but was on the bench for the 10-2 Celtics run to start the fourth that blew open the game.

Mitchell hit four of his five 3-point attempts in the third quarter to help Cleveland extend its lead to as many as 14 points. And he remained in the game at the start of the fourth and until the game was put away, with Cleveland up 27 and four minutes left.

"At halftime I was just like, 'I don't plan on coming out.' That was the mindset," Mitchell said. "He asked me if I needed (a break) and I was like, 'I'm good.'"

According to ESPN Stats & Information, the 24-point win was the biggest in the playoffs by a double-digit underdog since 1991.

Celtics center Kristaps Porzingis missed his third straight game with a strained calf muscle. Mobley started at center in place of Jarrett Allen, who has missed five straight games with bruised ribs, and reached a career playoff high in points.

Mobley scored 11 in the first quarter, when the Cavaliers quickly fell behind by nine - giving the vibes of a second straight blowout. But Cleveland ran off 11 points in a row - eight from LeVert. Boston went ahead by eight in the second before the Cavs sent it into halftime tied.

Tatum had 16 points, six rebounds and four assists at the half, and Mobley had 15, seven, and five.

The Associated Press contributed to this report.