The Celtics hold themselves to a high standard. Jayson Tatum, after Tuesday’s win over the Cavaliers, said they were the best team in the league. Before Thursday’s rematch, Derrick White said it’s important to continue that standard, especially as teams routinely give them their best shot.

That’s why, even in mid-December, Joe Mazzulla challenged the Celtics to treat this unique week like a playoff situation. And they knew after beating the Cavs in Game 1, putting them away in a second two nights later would be a great challenge.

The Celtics, in their first two-game series of the week, passed the test. It was certainly not their sharpest performance. They controlled the first half, but still left something to be desired. The Cavs, after a hot shooting display, cooled off and were still within striking distance. Another subpar Celtics third quarter let their visitors come back to life.

But like they’ve done several times this season, the Celtics held their composure under pressure. Jayson Tatum scored 27 points on a poor shooting night, and Brown scored 22 points after a hot first half, and the Celtics held on late for a 116-107 victory over the Cavaliers on Thursday night.

All five Celtics starters scored in double figures, including 18 from Kristaps Porzingis and 15 from Jrue Holiday as the Celtics held off Donovan Mitchell, Darius Garland, Caris LeVert and the feisty Cavs. They used hustle plays and extra effort to pull out this win. Al Horford was big off the bench. The C’s made enough winning plays to hold on, even after they nearly blew a lead they built as large as 15.

Suddenly, the Cetlics found themselves in a tight game to start the fourth quarter after Garland’s 3-pointer in the last second of the third quarter cut Cleveland’s deficit to just three.

The Celtics responded quickly, with a dominant stretch from Tatum to begin the fourth quarter. He hit a fadeaway shot to begin the period, then after Lamar Stevens corralled a steal, hit a 3-pointer. Moments later, he blocked Garland’s layup in transition, and it led to a Holiday layup for a 7-0 Celtics run and 10-point lead.

The game continued to hang in the balance midway through the period as the Celtics led by six. Holiday corralled an offensive rebound, leading to a second-chance triple from White. Two Tatum free throws restored the lead to 11. But the Celtics struggled to find the finishing blow. Garland made a 3-pointer and LeVert’s layup cut the Celtics’ lead to five with three minutes to go, forcing a timeout.

On the first possession after the timeout, Tatum forced a missed 3-pointer at the shot clock buzzer, but Brown was there to grab the rebound and found Holiday underneath for two. LeVert then dribbled the ball out of bounds, and Tatum took advantage by finding room for an easy dunk and 111-102 Celtics lead with 1:53 left. The Celtics were not threatened again.

Other takeaways from the win:

– Unlike Tuesday’s game, when the Celtics had a horrendous start and trailed by as many as 15 in the first quarter, the C’s were firing on all cylinders to begin Thursday’s rematch. Everyone had it going. Jrue Holiday made a terrific cut for two to start the game, Porzingis threw down an alley-oop dunk over Jarrett Allen and the Celtics were hitting their shots. They went 6-for-10 from 3-point range in the first quarter and despite some uncharacteristically poor passes that led to turnovers, held a comfortable lead for most of the first half.

The Cavs, who were hot from long range on Tuesday, cooled down on Thursday with a 4-for-20 mark from deep in the first half, which included several wide open looks. But Donovan Mitchell’s shot-making was up to par – 21 points on 8-for-12 shooting – and even though they forced the Cavs into 11 first-half turnovers in addition to their poor outside shooting, the Celtics only led by 11 at halftime.

– Brown was initially questionable for Thursday because of a left ankle sprain he suffered during Tuesday’s win, but he looked unaffected with a hot start as he scored 18 points on 8-for-11 shooting as he scored in a variety of ways in the first half.

– Without Luke Kornet, who was a late scratch on Thursday due to an adductor injury, the Celtics had just two available big men in Porzingis and Al Horford, so they assigned Lamar Stevens his first minutes since Nov. 28 and his first real meaningful minutes of the season, and against his former team. It didn’t go well in his first three-minute stint in the first quarter, when he was whistled for a defensive three seconds violation and then picked up three quick personal fouls. But Mazzulla re-inserted him in the fourth quarter and he made some productive plays. On a second chance after a Horford offensive rebound, Stevens cut to the basket and Horford found him for an easy dunk.