Celtics big man Aron Baynes hit Irving while trying to defend a Kemba Walker shot attempt. After fouling Walker on a drive, Baynes spun to box out and his right elbow smashed Irving, who immediately collapsed to the floor clutching his face.
Irving was attended to by Celtics trainer Art Horne and left the court clutching a towel over his bloodied face.
After the game, Celtics coach Brad Stevens said Irving went home at halftime but texted the team congratulating it for its 11th straight win. He added that Irving has not been diagnosed with a concussion but will be monitored for symptoms moving forward.
"I haven't talked to him," Stevens said of Irving. "But he sent a text to a group of us right when we walked back into the coaches' office and it said, 'Way to go. Great win' ... So obviously he watched the end of the game."
Even without Irving, the Celtics continued their winning ways. They erased an 18-point deficit to win their 11th straight after an 0-2 start to the season. Backup point guard Shane Larkin tied with Jayson Tatum for a team-high 16 points after Irving was injured.
"Once we figured [Irving] wasn't coming back -- at the end of the day we're still NBA players," Marcus Morris said. "Like I said when Al went down, it's next man up. Shane [Larkin] did a hell of a job coming in, taking that load and scoring the ball. The crowd was great so we pulled that one out."
Added Terry Rozier: "We've been preaching next man up forever. Lately, our team is dropping like flies. You just gotta be ready. Shane did a great job, stepping up, coming in today. Like you said, you just never know in this league when your number is going to be called. We did a good job handling that."