PORTLAND, Ore. -- Isaiah Thomas had two points in the first quarter, the Portland Trail Blazers were mounting a double-digit lead, and things were not looking good for the Boston Celtics.

Then Thomas got untracked, bombing in 34 points overall as the Celtics raced to a 120-111 victory Thursday night at Moda Center.

Thomas made only 11 of 26 shots from the field, 2 of 11 from 3-point range. However, the 5-foot-9 point guard drove to the basket with ease for eight layups, and he made 10 of 11 free throws.

"I was missing easy shots all night long," he said. "I had a tough night offensively, but I just stayed the course. I knew a few of them would fall."

Thomas led seven Celtics in double-figure scoring. Marcus Smart had 18 points to go with six rebounds, five assists and five steals, and Jaylen Brown scored 14 points for Boston, which won for the eighth time in nine games.

Damian Lillard scored 28 points and Al-Farouq Aminu added a season-high 26 for the Trail Blazers, who lost for the third time in four games.

The Celtics scored 43 points in the fourth quarter -- the most an opponent has scored in any quarter against Portland this season. Smart was in the middle of it with nine points on 4-for-4 shooting to go along with two rebounds and a steal down the stretch.

"When you want to be a championship team, you have to have guys like (Smart) on your team," Thomas said. "He does stuff that's not on the stat sheet."

Portland coach Terry Stotts said, "We didn't make enough winning plays at the end to win the game. Those are the types of things you have to do at the end of a close game to win. They made those plays, and we didn't."

Thomas scored 14 points in the second quarter, seven of them in a late run that cut into what was once a 17-point deficit and got Boston within 55-49 at the half.

"The end of the first half was outstanding," Boston coach Brad Stevens said. "And the start of the second half said we were going to be in the game."

Boston (34-19) outscored Portland 10-2 to begin the third quarter and grab a 59-57 advantage. The Celtics took a 77-76 lead into the final period.

Thomas' three-point play gave Boston a 92-88 edge with 7:36 remaining. The Celtics kept the lead at two to four points until Smart's rebound basket made it 110-104 with 1:39 to play.

Brown padded the lead to 112-104 on a pair of free throws with 1:12 to go.

Thomas' driving layup increased the margin to 114-104 with 57.2 seconds to play.

Portland's Allen Crabbe buried a 3-pointer to cut it to 114-107 with 47.1 seconds remaining, but Thomas followed with a pair at the line, and it was 116-107 with 46.1 seconds left.

Lillard scored on a layup, but Smart converted a layup at the other end, finishing off Portland (23-31).

"We have to be able to finish the first half better," Lillard said. "We wanted to push the lead to 20 (instead of see it dwindle to six). That was our first mistake.

"They're the second-best team in the East right now. You give them life, they feel like they're still in the game, and they can take it over. It got down to the stretch, they made those plays you need to make."

NOTES: Boston G Isaiah Thomas scored 20 or more points for the 37th consecutive game. In 15 of those contests, he had at least 30. ... F Evan Turner missed his first game since breaking the third metacarpal bone in his right hand in Portland's win over Dallas on Tuesday. The injury is expected to keep him out of action for five to six weeks. Moe Harkless started in Turner's place and scored four points. ... Boston F Jae Crowder missed the game to tend to family health issues in Dallas. Marcus Smart started in Crowder's absence. The Celtics are uncertain if Crowder will be able to rejoin them in Utah for their Saturday game. "It's whatever (time) he needs," coach Brad Stevens said. ... Stevens, on Boston's 108-92 loss at Sacramento on Wednesday despite the Kings missing suspended C DeMarcus Cousins: "(The Kings) were the best team on that night. That's basketball. The game starts 0-0. If we don't play well, we get beat."