The Bulls brought back veteran guard Mike James on Thursday. Since he's already been through two 10-day contracts with the Bulls, by rule they had to sign him for the rest of the season.
James, 36, was in uniform against Boston.
"We actually liked what he brought to our team before," coach Tom Thibodeau said. "He gives us the flexibility to play two point guards. He has size, veteran experience. He knows what we're doing. Just more of an insurance policy."
James, who has played in eight games, arrived along with questions about C.J. Watson's health. Watson came back early from a sprained left ankle when Derrick Rose went on the shelf. In the last four games, Watson shot 21.9 percent from the field (7-for-32).
Asked if Watson could use some time off when Rose returns, Thibodeau said it's possible.
"It's a good question and I think this time of the year, you have to strike that balance of rest and playing," Thibodeau said. "We also want him to be in rhythm down the road. The way the schedule is this month, if we need to sit him out of some practices, we'll probably do that, give him an opportunity to rest there. He's done a good job for us overall."
Old and effective:
Celtics coach Doc Rivers talked Thursday about the aging "Big Three." Of the group that came together to win a championship in 2008, Paul Pierce is 34, Kevin Garnett 35 and Ray Allen 36.
Rivers mentioned that Garnett has had to adjust his game to deal with injuries and Allen isn't as quick as he used to be.
"I don't know if Paul's changed at all, to be honest," Rivers said. "Paul's got a timeless game. It never looks like he's going that fast, never looks that athletic. Then after the game, you look at the board and he's at 26 points and 14 rebounds, or something, and you're thinking, 'How did that happen?'"
Slow start forgotten:
Boston went 4-8 to start the season but won 15 of 21 games heading into Thursday's contest at the United Center.
"I felt the teams that came into the year with a chip on their shoulder, they attacked the season," Celtics coach Doc Rivers said. "Chicago, after losing to Miami, you could see it. They attacked the season from the beginning. Their young guys came into camp in great shape.
"I thought Miami, because of the (Finals) loss; Oklahoma, because of the (conference finals) loss, you can just see those teams in particular came in with something to prove. I thought everyone else pretty much struggled out of the gates. Now, I think, we're in shape. We're not healthy, but our team is ready to play now."
Before Thursday's game, Boston coach Doc Rivers said in his mind, NBA coach of the year is a two-man race between Tom Thibodeau and San Antonio's Gregg Popovich. ... Celtics guard Ray Allen returned from six games off with an ankle injury on Wednesday. Against the Bulls, Rivers decided to start Avery Bradley and bring Allen off the bench. It was just the fifth time in 1,145 regular-season games that Allen didn't start and the first since the 2002-03 season when he played for Milwaukee.