It's the fourth time O'Neal has missed a game this season, although two of those were to attend a family funeral. Joel Anthony started Monday night in place of O'Neal, who has been bothered by soreness in the groin and hip for about two weeks.
O'Neal is Miami's third-leading scorer at 12.7 points per game and second-leading rebounder at 6.9 per game.
The Heat are hopeful O'Neal could return Wednesday when Miami hosts Boston.