Lamar Stevens had an idea, but he didn’t know when the moment was going to come.

When Luke Kornet was ruled a late scratch from the Celtics’ lineup in Thursday’s win over the Cavaliers, Stevens thought there was a chance he could play his first minutes since Nov. 28. But he didn’t know until Joe Mazzulla called him from the bench to substitute for Kristaps Porzingis with four minutes, 20 seconds remaining in the first quarter to face his former team.

“That’s when I found out,” Stevens – who played his first three seasons with Cleveland before signing a partially guaranteed deal with Boston this season – said afterward with a laugh.

Stevens’ nine minutes in Thursday’s win was overall, unspectacular in the box score. The big forward was whistled for a defensive three seconds violation and three personal fouls in his first three-minute stint, but returned to produce good minutes late. He scored four points, and contributed a block and steal in the fourth quarter that helped the C’s close the victory. Mazzulla praised him for his physicality and stepping in admirably on short notice.

“I definitely think there are things that I can do a lot better, but in terms of conditioning and my preparation, I definitely feel like I’m ready for this moment and ready to help this team win,” Stevens said.

Stevens’ role is difficult. Especially on a team as talented as the Celtics, minutes are sparse. He doesn’t know when his chances will come. When he does get them, it can be difficult to find a rhythm or chemistry with players they don’t have many reps with. Personally, that can be challenging for a young player in the league fighting to prove themselves. But despite those circumstances, he must stay ready for his opportunities.

“I think it just comes down to just controlling what you can control,” Stevens said. “I mean, there’s so many things that are out of my control, whether I play or don’t play or how much I play, so I like to just focus on my preparation leading up to it and letting the chips fall where they may.”

Stevens’ role on a championship-ready Celtics team may not seem significant and he likely won’t play much, if at all, come playoff time. But while the Celtics boast the best top-six in the league, there are several nights over the course of a long season that the bench guys are important and will be needed in a pinch.

They call themselves the “Stay-Ready Group.” It includes Dalano Banton, who has made some productive spot starts. Neemias Queta, Oshae Brissett and Svi Mykhailiuk have given good minutes. On Thursday, it was Stevens’ turn. They’ve stepped in humbly and admirably for every chance they get, and that can only benefit the Celtics in the long run.

“We’ve got a really, really good team,” Jayson Tatum said. “I see the work that they put in every morning, every day, on off days, getting their reads in, getting their conditioning in and playing pick-up. Those guys are really, really good. They’ve been in the league a while – Oshae, Lamar, Svi, Neemy, DB. They’re all professionals and it just shows the depth of our team and the talent level of the NBA. I tip my hat off to those guys every single day for just staying with it. I know it can be tough. We all love this game, and everybody wants an opportunity. But as a professional, it’s your job to just stay ready, and I think they do that every single night.”

Added Stevens: “You just never know. You never know what can happen in an NBA game or how a coach may feel. So you just always want to be ready, always wanna be prepared because you never know when that number is gonna be called.”