He scored 22 points, but the Celtics lost 88-87.
"I felt great personally," said Allen, who was 9-of-14 from the floor. "I just tried to play. Going with how I felt, I was very aware of my body early and I felt great. As the game went on, I got to feeling a lot better out there."
But Allen ultimately was left wishing he finished with two more points. He missed a pivotal driving layup with 2:53 to play that would have put the Celtics up by nine, in the midst of the Cavaliers closing out the game on a 12-0 surge.
"By the time I got past (Anderson Varejao), I was wondering if I was going to have to do a reverse layup because I felt like he was still hovering over me," Allen explained. "And then Antawn Jamison rotated, so it was almost like I held onto it, thinking he was over the top of me, and I let it go too late as opposed to just getting it up on the rim."
Allen tweaked his left ankle last Sunday in Washington. He said it's difficult to properly describe the injury, saying it's not a turn or a sprain but more localized pain on the interior of the left ankle that the team dubbed a jam. Allen said he's comfortable where he's at in his recovery.
"I got up and I didn't have any issues or any problems," he said before the game. "When I shot today, I probably felt more weak than I (felt) pain. I moved around fine. The only thing I noticed was weakness in there, but it's just like running around on it and getting it stronger -- just from having been off of it. I like where I am. I like working my way through it as I go along because I'm not going to do anything worse to it at this point. I feel good about it."
"Ray looked good, he looked fresh," coach Doc Rivers said. "I thought he -- 9-for-14 -- in some ways you look at the stats, he was probably our most efficient player. You know, he missed the big layup down the stretch and I thought he gave up some middle drives and some baseline drives that creates those offensive rebounds that we talk about. And those are things we have to get better at. But overall, I couldn't have been happier with his play."
Elsewhere on the injury front, Jermaine O'Neal sat out after Rivers deemed the center a game-time decision, saying it was still 50/50 whether he'd play while meeting with reporters an hour before tip-off. Rajon Rondo (right wrist) and Keyon Dooling (right hip) were inactive.
"Rondo is out for tonight, but maybe (will play) our next game," said Rivers, whose team plays Tuesday at Cleveland. "Keyon's out, and he'll be out the longest of all the guys."
The Cavaliers were without Daniel Gibson, who is sidelined by a neck injury.
Chris Forsberg covers the Celtics for ESPNBoston.com. Greg Payne provided information for the report.