The Cleveland Cavaliers became the first team to collect three overtime wins against the same opponent in one season since 2004-05 after Monday's 118-114 comeback against the Boston Celtics.

Cleveland trailed by 12 at half-time, and 14 at three-quarter time, but clawed back late to force an extra period – thanks to some heroics off the bench from Lamar Stevens and a forgettable trip to the free throw line by Grant Williams.

After not playing a single minute through three quarters, Stevens was injected into the game to start the fourth and ended up not coming out the rest of the way. He racked up eight rebounds, including six big offensive boards, to go with eight points and an assist in the fourth quarter and overtime.

But the game would not have even reached overtime if Williams was able to hit a free throw with 0.8 seconds remaining in regulation, missing both attempts to leave the game tied.

All-Star Donovan Mitchell led the Cavaliers with 40 points on 14-of-34 shooting, but after the game head coach J.B. Bickerstaff made it clear who the most valuable player was.

"There is no way we win that game without Lamar," he said. "He changed the tone, the physicality, the effort.

"When we have our conversations with guys, we talk to them about who we need them to be, and how they play to their strengths that impacts this team in the most positive way – and Lamar is a dog.

"He is willing to scrap, he's willing to fight, he's not afraid of the moment. He hit the big three, then he drives down the lane with the physical finish, and every time we needed an extra possession he went and got it.

"I can't say enough of how proud I am of him, and how deserving he is of a ton of credit for us winning this game tonight."

For the second game in a row, Stevens was a recipient of the Cavaliers' 'Junkyard Dog Chain' that they award to the grittiest and toughest performance of the night, and Mitchell highlighted how enormous it was for the undrafted 25-year-old to show up in such a high-pressure environment.

"We couldn't really afford to lose this one," he said. "I don't know what the standings are exactly, but I know we're only a game, or two games [clear in the fourth seed] – so this was important.

"This was huge, they were up the whole game, getting whatever they wanted. We just kind of, as a group, needed that spark, and Lamar [Stevens] came in and gave us one. I just wanted to find ways to do it myself as well, and it led to a win.

"When Lamar speaks, you listen. That's something that you earn. I've only been here a few months, but you can tell that as a locker room and as a group of guys, we trust in him, and his voice, and his leadership.

"When he's out there competing, fighting, screaming, getting buckets and also getting stops, you gotta be out there doing the same thing, because you don't want to let Lamar down.

"That's what he provides for us, he's always been that way, and it's great to see a lot of his hard work starting to come out for everybody to see."

Having earned the second spot up on the post-game media podium alongside Mitchell, Stevens spoke about his mindset about how to help his team win as a role player in limited minutes.

"Coming from where I came from, being undrafted, I don't take any moment for granted," he said. "I always want to be ready for any opportunity that comes my way.

"From what the team asks for me and what J.B. [Bickerstaff] asks from me, it's not just to come out and score big numbers, it's just to impact the game and bring that physicality, and defense, and do the things that I know I can control."

He also touched on why he believes his Cavs have been so effective in overtime situations this season, having come through an extra session unscathed against the Celtics on both October 28 and on November 2.

"I think at the beginning of the year, coach made a huge emphasis on us being the most conditioned team," he said. "I think that's just what we are. 

"We're ready when it comes down to winning time, I think we get a little bit closer together, and we're able to pull out some big-time wins by just trusting each other and knowing that we're prepared for that moment."

Mitchell, who is a vice president of the NBA Players' Association (NBPA), also shared some insight into the conversation he had with Williams – the first vice president of the NBPA – before his two crucial misses.

When asked to confirm if Williams told him beforehand that he would make both, Mitchell responded "yeah, he did".

He continued: "We have a [Players' Association] call on Thursday or Friday, so I was just like 'let's just miss one and talk about it, let's see what happens'.

"He gave us both, and I almost lost us the game because I didn't box out Marcus Smart and he came in for the tip, so that's what I'm really thinking about that moment. He missed both free throws, but I have got to be able to box out in those moments.

"I mean, you're just trying to mess with mentally, just see what happens. I have no doubt in my mind that if Grant's in that position tomorrow, or the next day, he'll make both free throws.

"He's a good player, I'm just trying to find a way to get in his head a little bit."