Bodies bouncing around like billiard balls. Shots hitting the rim with a dull thud or a resounding clank. Every possession turning into a hard slog through a wet bog.

Last night was not a night of beauty at the Garden with one exception: the Boston Celtics gave you another reason to love them.

Undermanned, dog tired, physically beaten up and mentally beaten down they had every reason on this final game before the All-Star break to check out. Instead they checked one of the best defensive teams in the NBA and ground them down, beating the Chicago Bulls at their own game to win for the eighth time in their last nine starts, 71-69.

This was not supposed to be what happened after Rajon Rondo went down for the season with a torn ACL and soon after rookie Jared Sullinger followed with lumbar disc surgery and then two nights ago Leandro Barbosa disappeared for the duration, another ACL torn and perhaps more significantly his teammate’s hearts as well for this last injury gave them every reason to do what they refuse to do.

“This team is tough,’’ Paul Pierce said after struggling with a 2-for-12. “Mentally you’ve got every reason to just be out of it each and every night. Use the injuries for an excuse. Use the emotions, the fatigue, so many excuses are available to us but somehow, some way, we continue to fight through it mentally.’’