For the first five minutes of the game, the Celtics were virtually unstoppable. They opened the game on a 22-3 run.

Jayson Tatum and Jaylen Brown were on their way to combining for 83 points. They were spraying the ball around the floor and finding open threes with ease.

It was the kind of run that would have made many teams fold. But, not Cleveland. They held their ground, made a gritty comeback, and tied the season series with Boston at 2-2 with a 123-116 win.

“Everything that could have possibly went wrong went went wrong,” Cavaliers guard Donovan Mitchell said. “At that point, it’s like, you can only go up from there.

‘Give them credit, they started the way they were supposed to but for us, we’ve given up 38-point quarters before … even when we got the lead, just still being consistent. That’s the biggest challenge. It’s been my challenge all year. How do you respond? And we did.”

Cleveland, which holds the best record in the NBA, showed why they are atop the Eastern Conference standings.

“It means we’ve got grit,” Mobley said. “No matter how down bad we get, we’re going to keep fighting, keep going all the way to the end of the game. Tonight we kept fighting.”

Beating the defending champions on their home floor with Tatum at his best (46 points, 16 rebounds, 9 assists) is always a difficult task. It was a good way for Cleveland, which was eliminated by the Celtics in the conference semifinals last year, to take stock of where they are at this year, Mitchell said.

“At the end of the day, we’ve done a lot of really good things this season. I keep telling my guys, we haven’t done anything,” Mitchell said. “All the hype, all the 15-0, that’s great but we haven’t done anything yet. This is a measuring stick. These guys have won a championship and we want to continue to get to where they are at and we saw that and we took steps.”

Cavaliers coach Kenny Atkinson noted that the Celtics were without two starters. Kristaps Porzingis was sick with a non-COVID illness, and Jrue Holiday was sidelined with a finger injury. Still, it was an encouraging win, he said.

“The more you play these guys, or these elite teams, you get great feedback on what works, what doesn’t work, what could possibly work if you have to play them in the playoffs,” Atkinson said. “But, I don’t know it doesn’t feel like this game is like ‘oh, we’re over the mountaintop. By no means. No Porzingis, no Holiday. I do like getting the win, makes us a little more confident in our mentality if we have to play these guys in the playoffs.”

Games like Friday night’s win are what players play for, Mitchell said. But, there is still work to do for Cleveland to prove it is capable of dethroning the Celtics.

“Coming into the game, like I said, no championships were won tonight,” Mitchell said. “I was kind of saying ‘Alright, we got punched in the mouth’. What are we going to do about it? How are we going to respond? Tonight was another example, just in front of a larger audience.”