The Celtics' Eddie House then tacked on a free throw. With 1.8 seconds left, the Sixers inbounded on their end of the court but managed only a one-dribble, 30-footer by Iguodala that was not close.
Iguodala finished with 25 points.
"I thought through the whole game we played hard," Sixers coach Tony DiLeo said. "It was disappointing we didn't execute down the stretch offensively."
The Celtics were without Kevin Garnett, out with a knee injury, and Ray Allen, suspended for one game by the NBA. They were with Pierce, who played only a few minutes of the back-and-forth final quarter.
Iguodala was asked if he could find any positives in the loss.
"Um, not really," he said. "They weren't at full strength. It was their second unit. So I don't see any."
The Sixers had power forward Thaddeus Young back in the lineup after missing seven games with a sprained right ankle.
Except for one unfortunate first-half play when Young tried exploding off his right foot for a lefthanded jam only to find himself a few inches lower than normal, the rim too high for his attempt, Young looked like his pre-injury self, scoring 18 points.
"That was the one real positive," DiLeo said. "He didn't seem to miss a beat."
The motivation - Celtics had none, Sixers had plenty - made this a tough-to-lose game for the Sixers.
But they did.
Their sixth straight loss kept the Sixers, now 40-41, in the seventh spot in the Eastern Conference, a game behind the Chicago Bulls. It left them with only one game - tonight in Cleveland - to avoid entering the playoffs on a losing streak. It ensured that if they are to improve on last year's record of 40-42, it will be by only one game.
And it left these scenarios for tonight: If the Sixers win at Cleveland and Chicago loses to Toronto, the Sixers clinch the sixth spot. If the Sixers lose, the Bulls clinch the sixth spot.
Tonight, the Cavaliers will be playing for a 40-1 record at home, which would tie them with the 1985-86 Celtics for the best home mark in NBA history.
This year's version of the Celtics improved to 61-20 but had already locked up the second seed in the East.
Last night, Pierce was the last superstar standing for Boston, the guy who told coach Doc Rivers he wanted to play, not rest. Pierce scored 31 points, hit seven three-pointers, and basically willed his team to victory.
A victory the Sixers very much needed.
Contact staff writer Kate Fagan at 856-779-3844 or firstname.lastname@example.org.