Jimmy Butler was a surprise starter in Sunday night’s 104-97 win over the Timberwolves at the Target Center, but he was prepared.

Marco Belinelli—who himself is a fill-in starter because of veteran Rip Hamilton’s absence—missed the contest due to abdominal muscle strain, an injury he’s been playing through for some time now, something Bulls head coach Tom Thibodeau neglected to inform the media before the game.

Afterwards, he provided some clarity.

“He’s been battling the abdominal muscle strain,” Thibodeau said. “Just couldn’t get going today.”

“I was hopeful [Belinelli would play] this morning. We did the walk-through right before and I knew it wasn’t looking good,” he continued. “I don’t want to speculate right now. I’m hopeful that in a day or two, it’ll calm down and he’ll be okay, but he’s day-to-day.”

Either way, Butler showed that he was more than capable of being a temporary replacement at shooting guard, scoring 20 points, snatching nine rebounds and swiping three steals, as well as guarding a variety of players, from Minnesota starter Luke Ridnour, more of a point guard-type, to bigger forwards, such as Derrick Williams.

“He had to guard a small, he did a great job with his defense, posted, played hard, made hustle plays,” Thibodeau said of Butler’s play. “He was huge.”

All-Star teammate Luol Deng chimed in: “Guys stepped up. Didn’t know until this morning that Marco wasn’t playing. Jimmy did a great job of stepping in and filling in, and guys off the bench did a great job.”