Illinois coach Bruce Weber had no intention of putting Calvin Brock back into the game.

The sophomore from Chicago Simeon had played four minutes in the first 27, scoring two points, pulling in one rebound and being charged with one turnover.

“He had thrown three passes to everyone but us,’’ said Weber, exaggerating a little bit. “I’m not sure I was ready to put him back in, but matchupwise the coaches thought we should go with him.’’

It’s a good thing that Weber listened to his assistants.

Brock came off the bench to provide Illinois (12-2) with a much-needed spark as the Illini rallied from a 46-40 second-half deficit to beat the Idaho State Bengals 71-60.

“This was a game about our toughness and maturity to get a win like this,’’ said Brock ignited an 11-0 run with his baseline jumper with 10 minutes, 42 seconds left.

The 6-foot-5 guard capped the spurt with a 15-footer 2:40 later to give Illinois a 51-46 lead.

“Coach put me into the game at that point so that we could have both myself and Brian Randle flashing into the middle of their zone defense,’’ said Brock, who wound up with seven points, six rebounds and one critical block shot for the Illini. “When you can get the ball to the middle, it just breaks down the defense.’’

Brock admitted the Illini, who were coming off an emotional win over Missouri on Tuesday, started looking ahead after they got a 29-13 first-half lead.

“Everyone is so excited to go home. We usually go home after Missouri game,’’ he said. “Give them credit, they came out with energy and we were thinking about going home and celebrating Christmas, getting those days off.’’

Illinois sophomore point guard Chester Frazier, who hit a handful of key 3-pointers in the second half including a moon shot off a Brock offensive rebound as part of a 24-7 Illini run.

“He brought us energy,’’ Frazier said of Brock. “He came off the bench, got a few rebounds, hit a few jump shots, and made a crucial blocked shot.

“He just brought us a lot of energy.’’

Weber pointed out that the 16,618 were very quiet when Idaho State took the lead.

“It was dead quiet in that place,’’ the Illinois coach said of the Assembly Hall. “You are down and they are making banked 3s.

“We could have doubted and quite, but we didn’t. They showed some character in the second half.’’

It also didn’t hurt that the Illinois sports marketing department played a taped message from former Illini standout Brian Cook.

The current Los Angeles Laker implored Illinois fans to make some noise.

All of the sudden during the timeout, fans mostly clad in orange, rose up and turned the decibel level at the Assembly Hall up to its highest level of the night.

“That was awesome,’’ said Brock. “We knew that we had to pick up our intensity on the defensive end and then here are the fans giving you a jump start.

“It was exactly what we needed at that point.’’

Brock admitted that his early-season playing time helped him be a factor on Thursday night.

“The old me, probably would have passed up the mid-range shot and I probably would not have went to the boards as strong,’’ he said. “Getting playing time early in the year and starting has given me a boost of confidence when I do get into the games.’’

Brock was part of a 31-12 advantage for the Illini in bench scoring. Sophomore guard Jamar Smith led Illinois with 21 points off the bench, while Brock had seven and Trent Meacham added three.

Illinois teams are 62-6 under Weber when the bench outscores the opposition.

“Those 31 points are probably the difference in the game for us,’’ Weber said.

While the Illini, playing with leading scorer Warren Carter, still managed to have four players in double figures and they didn’t have a player in the game for more than 35 minutes.

While Idaho State (5-7) had its top two scorers, Akar Abdul-Ahad (24) and David Schroeder (16), play the entire contest.

“Their depth made a difference,’’ said first-year Idaho State coach Joe O’Brien, who had coached for four seasons at Lincoln College.

So, coach was exactly were you thinking when you led Illinois 46-40 with less than 11 minutes remaining.

“I was just thinking that I hope we have enough gas in our tank to finish this thing,’’ he said.

For the fourth time this season, the Bengals allowed a major program to slip past them.

Marquette, Brigham Young and Washington State had done the honor before against Idaho State.

Illinois is idle until Dec. 29 contest in Cincinnati against Xavier. It will be the final non-conference contest of the year for the Illini, who open Big Ten play on Jan. 3 at Michigan.