Penny Hardaway scored 27 points and the Orlando Magic held the Celtics without a field goal in the final 3:54 to beat Boston 104-99 Friday night.
Rony Seikaly and Darrell Armstrong each had 17 points and Horace Grant and Brian Shaw made two free throws apiece in the final 19 seconds.
Next up is a game Sunday afternoon against the Los Angeles Lakers, who will be without Shaquille O'Neal.
"Hopefully we won't be overanxious," Hardaway said. "They are the team that took our big man away and we feel he should have stayed home."
Rookie Antoine Walker had 19 points and a career-high 21 rebounds for Boston, which lost for the 23rd time in 25 games. David Wesley also scored 19.
Orlando took a 97-95 lead with 4:25 left on a jump shot by Seikaly. The Celtics then got a layup from Dee Brown and two free throws by Eric Williams to take a 99-98 lead with 2:15 left.
Seikaly's turnaround jumper with 2:00 left gave the Magic the lead for good, and the Celtics failed to score in their last six possessions. Williams and Brown missed open three-point shots in the final 14 seconds.
"I had a great look from my favorite spot on the court," Brown said. "I live for a situation like that, but the shot didn't fall."
The win was the Magic's eighth in its past 11 outings.
"I feel good (about the win)," coach Richie Adubato said. "If you consider everything, it is very hard to get your team to play hard (in back-to-back games)."
"We have had a brutal schedule lately," Hardaway said. "In the fourth quarter I was a little fatigued."
Two three-pointers by Wesley were the keys to the Celtics' 16-6 run at the start of the third quarter. Wesley hit his second with 8:32 left to give Boston a 65-62 lead, its first since the opening minute of the second quarter.
The Magic scored the last three points of the third quarter, including a driving layup at the buzzer by Hardaway, and took a 85-80 lead.
Seikaly, with 15 rebounds, has a team-high 26 double doubles this season after having 15 last season.
Hardaway scored 17 points and shot 6-for-7 from the field in leading the Magic to a 59-51 halftime lead.
"Antoine was spectacular on the boards," Celtics coach M.L. Carr said. "We ran into a veteran team who got the ball to Penny and he delivered."