Brewer sprained the thumb on Tuesday night during the second quarter of a game against the New York Knicks while diving for a loose ball. He had X-rays that came back negative. A team spokesman said Brewer will be re-evaluated Wednesday by team physician Dr. Brian Cole and the hand specialists at Midwest Orthopedics.
Brewers said initially he feared the worst.
"When I first did it, I thought I broke it," Brewer said. "Because it swole up instantly and I was like, 'Oh, man. Not with two games left, I broke my thumb.' Even if that was that was the case I was going to try to get it taped and play through it. But I'm glad it wasn't a break or anything."
Brewer left Madison Square Garden wearing a brace around the thumb and admitted he was feeling pain.
"It's just stiff," he said. "I've been icing it the whole game. We'll see how it feels [Wednesday] and try to give it a go."
Whether Brewer plays or not on Wednesday, he is determined to play in Game 1 of the playoffs against the Indiana Pacers this weekend.
"If it's still attached, I'm going to try to be out there," Brewer said.
Bulls center Joakim Noah also tweaked his already sprained right ankle on Tuesday during the fourth quarter, but he said he felt fine.
"I'm OK," Noah said. "I'm good. I'm fine. I just fell on my ankle a little funny, but I'm fine."
Noah was taken out of the game after tweaking the ankle, but Bulls head coach Tom Thibodeau tried to put him back in before the final buzzer sounded. He didn't seem concerned about his center's health.
"He said he could go back in," Thibodeau said. "I liked his energy a lot tonight. I thought he played well."
Nick Friedell covers the Bulls for ESPNChicago.com and ESPN 1000.