With 4 1/2 minutes left in the third period in Boston Garden, Larry Bird jumped off the Celtics' bench and ran to the dressing room with trainer Ray Melchiorre in hot pursuit.
Bird, plagued by foul trouble after scoring 20 points in 16 minutes of action in the first half, returned and helped the Celtics hang on against rallying Milwaukee in Boston's 40th NBA home opener.
"They (Bucks) were hanging tough, and even though Larry had four fouls we wanted him back in there for the start of the fourth period," Coach K.C. Jones explained. "He's had problems with his back, so he went to the dressing room to warm up a little."
Bird scored only two free throws after his return, but set up four baskets with sharp passes and grabbed a couple of key rebounds.
Dennis Johnson scored seven points in a two-minute span midway through the fourth quarter and the Celtics pulled away again against the only team to beat them four times in the 1984-85 regular season.
Kevin McHale scored 25 points, Johnson 24, Bird 22 and Robert Parish 20 as Boston won its seventh consecutive home opener and its 28th as a charter member of the NBA.
Boston built a 17-point lead early in the second half and was ahead 87-78 heading into the final period. The Bucks closed to within three points three times and trailed by just 98-92 when Milwaukee Coach Don Nelson was hit with two technical fouls and ejected with just over six minutes remaining.
Johnson cashed one of the two technical foul shots, plus two more free throws.
Sidney Moncrief scored on a layup for Milwaukee but Johnson padded the Boston lead with two baskets on feeds from Bird.