INDEPENDENCE, Ohio - The Bulls are again missing one of their big men.

Chicago forward/centre Pau Gasol will sit out Tuesday night's Game 5 against the Cleveland Cavaliers with a strained left hamstring, an injury he sustained in Game 3 of the series and also kept him out of the Game 4.

Gasol was a game-time decision, but coach Tom Thibodeau announced about 90 minutes before tip-off that he will be without one of his best scoring options in a pivotal game in the Eastern Conference semifinal. Gasol said the injury is better but not good enough for him to be active or help his teammates.

"We're doing everything we can to get me on the floor as soon as possible," Gasol said, "but at the same time hamstring strains are very tricky. I've had two in my career and one I was out for a month, and the other one I was out for 2 1/2 weeks. It's been four days since this one. I don't anticipate being out that long otherwise I would be pretty much done."

Gasol sat out Sunday's game, when LeBron James made a buzzer-beating shot to give Cleveland an 86-84 victory and even the best-of-seven series.

Taj Gibson will start for Gasol, who has averaged 15.1 points in nine post-season games. With Gasol out, Gibson and Joakim Noah will get more playing time and rookie Nikola Mirotic may be counted on for more scoring. Thibodeau said the Bulls will need to adjust if Cavs coach David Blatt uses a smaller lineup.

"We're going to have to be ready," Thibodeau said. "We've dealt with a big being out most of the season. Niko has great versatility and he can play the 3 and the 4 and also because of the way they downsize, we're going to have to be ready for that as well. Joakim and Taj have played very well together as have Taj and Niko and we will look at the different combinations."

The Cavs, too, have key injuries as James is nursing a sprained left ankle and All-Star guard Kyrie Irving is hobbled by a sprained right foot and tendinitis in his left knee.

James rolled his ankle in the third quarter Sunday, but played the rest of the way. He had the ankle wrapped at the team's morning shootaround and said he had not yet tested it.

"It's been better. But it's been worse," he said. "I'll be ready to go."

Irving has been slowed by the foot injury since Game 2 of Cleveland's series against Boston. An MRI taken Monday revealed the tendinitis, but although Irving's speed, mobility and quickness have been compromised, he's going to do anything he can to keep playing in his first post-season as a pro.

"I can't do it," Irving said of the possibility of resting. "Mentally, I can't do it. I can't look myself in the mirror and sit on the bench or sit in the locker room while I watch my teammates go out there. I'd rather give 30 per cent, 40 per cent, rather than give none at all. I can't sit on the bench and be hurt and be OK with that. I still know I can be effective."