With Celtics fans in a frenzy throughout TD Garden after the Boston Celtics blitzed to a 25-3 lead over the Cavaliers in the final matchup of Eastern Conference frontrunners, Cleveland star Donovan Mitchell didn’t panic.

He actually was in a calm place.

“Everything that could have possibly went wrong, went wrong. At that point, you could only go up from there,” Mitchell said after posting his first 40-point game this season. “That’s been our challenge all year. How do you respond? And we did.”

What followed was three quarters of frenetic basketball that concluded with 41 points by Mitchell and a breakout night by teammate Evan Mobley that added up to a 123-116 win and a ninth straight victory by the Cavs team that earned a season split with a Celtics team they could very well see in the playoffs. The Celtics led throughout before the Cavaliers settled in and took their first lead of the game, 104-101 in the fourth quarter. Cleveland stretched its lead to 114-110 when the Celtics got back-to-back stops, each followed by buckets by Jaylen Brown to tie the game. Mitchell scored on a floater to put the Cavaliers back in front. Then, following a miss by Brown on Boston’s next possession, Mitchell hit a driving layup and was fouled. He completed the three-point play to put the Cavs in front 119-114 with 1:57 remaining.