Brandon Bass, Marquis TeagueBOSTON — Paul Pierce stood ramrod straight in the home locker room at TD Garden, doing his best not to look completely exhausted, even though the signs revealed the truth.

Pierce had just finished shooting 2-for-12 from the field on Wednesday while looking bogged down at both ends of the floor. Kevin Garnett was in a side room getting treatment after turning down Celtics coach Doc Rivers‘ offer to let the 36-year-old big man sit this one out. Jared Sullinger was in the building, but he and his surgically repaired back departed swiftly after the Celtics gutted out a 71-69 win over the Bulls without him. Evidence of fatigue was everywhere as the Celtics prepared to part ways temporarily for the All-Star break.

“It’s coming at the right time,” Pierce said of the break. “Some of the things that have gone on over the last few weeks for us have been tough — mentally, physically — so I think this is the perfect time for a break.”

The Celtics survived another wrestling match with the Bulls, a mirror image of the Celtics in style and in overcoming injuries to key players. Both teams shot less than 37 percent from the field on Wednesday, with neither team cracking 40 points until midway through the third quarter. The Bulls were playing without Derrick Rose, their All-Star point guard and former league MVP, as they have all season. The Celtics were soldiering on with Rajon Rondo, their own All-Star point guard, as well as Leandro Barbosa and Sullinger. All three suffered season-ending injuries within the last three weeks.

This five-day break therefore is a welcome respite for a group of players stretched to their limits. Thanks to the slew of injuries, the Celtics have been forced to find heroes in odd places. Against the Bulls it was Brandon Bass, who scored a game-high 14 points and assisted a crucial basket by Garnett in the closing seconds. With Rivers monitoring Garnett’s minutes — the coach had wanted his center, who will be the only Boston player taking part in All-Star weekend, to spend the entire game on the bench — Bass came through with his best game in months. He did so against a formidable Chicago front line of Joakim Noah, Carlos Boozer and Taj Gibson, no less.

“Games like this, you feel great after you grind it out, because this was a hard game for us,” Avery Bradley said. “We have guys that are tired. Mentally, people are already ready for a break. For us to win this game is big for us.”

When the Celtics reconvene next week to begin a five-game Western Conference road trip, they will be struck once again by the harsh reality of their situation. They still have only three healthy guards on the roster, and team president of basketball operations Danny Ainge could make a move to bolster the team’s depth any time before the Feb. 21 trade deadline. The Celtics are basically right at the luxury tax threshold, so help will be difficult to find via free agency. Nothing will get any easier, but after finishing the first half of the season with eight wins in their last nine games, the Celtics sound like they would prefer to keep the bulk of this group intact.

“This team is tough,” Pierce said. “It is, mentally. You’ve got every reason to be out of it each and every night. You could use injuries or fatigue or your emotions. So many excuses are available to us, but somehow, some way, we fight through it.”

That toughness has Jason Terry believing the Celtics will not crumble in the second half, once they receive some deserved time off.

“This is a great time [for a break],” Terry said. “We need it. Obviously, this whole ride has been mentally draining for us, losing guy after guy, but just being a veteran player in this league, you need to step away for a second, re-gather yourself and then get ready for this magical run, because it is going to be magical, and we all believe that.”

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