Milwaukee captured the final meeting between the teams this season despite blowing a seven-point lead late in regulation.
"I just love playing against KG. He's one of the guys I liked watching growing up," said Sanders, breaking into a smile when asked if it was something about seeing Boston that brings out his best.
The Bucks won for the sixth time in eight games, taking three of four against the Celtics, who had a five-game home winning streak snapped despite 35 points by Pierce.
Pierce, who had sent the game to OT with a 3-pointer with 2.5 seconds left, was blocked by Sanders as he attempted a tying 3 in the closing seconds of OT.
"I knew if he got it off he had a pretty good shot at making it," Sanders said. "It probably would have been bottom."
With the Bucks leading 97-94, Pierce came off a screen, got open briefly on the right wing before Sanders came flying out. Sanders then broke down court for a dunk to seal it.
"He's the only one that really had it going," Rivers said of Pierce. "I always jokingly -- and it's the truth -- say, 'It's a make-miss league' and tonight was evident of that."
Jeff Green scored 14 points and Garnett had 12 on 6-of-22 shooting. The Celtics shot just 38 percent, with Jason Terry going 1 for 15.
Pierce had scored a season-high 40 points in Boston's previous game.
"I think right now, it's this point in the season where I'm in a good groove," Pierce said. "I'm feeling good about my shot. I'm feeling good about my pace of the game. I'm just trying to do what I can to help this ball club win."
But he didn't have a chance on the last shot.
"I thought I got fouled on it," he said. "But you know, that's the way the game goes sometimes."
Terry was also 5 for 17 in a loss the last time against Milwaukee.
"That was frustrating. For me, being a shooter, you're getting looks that you want and they're not falling for you, especially when your team needs you most," Terry said. "Again, I'll take this on my shoulders. Maybe it's the Bucks? I don't know. That's two tough ones for me against them."
Green had to leave with a towel over his left eye in the closing seconds of OT. The Celtics said he had a bruised left cheek and chipped teeth.
In overtime, Ellis' consecutive baskets, coming nearly two minutes apart, had given the Bucks a 94-90 lead with just over a minute to play. But, like in regulation, Pierce made a jumper and Garnett hit a long jumper, tying it with 37 seconds left.
"The fact that we showed some resolve was a good sign for us," Bucks coach Scott Skiles said.
After a timeout, Ellis was fouled by Courtney Lee and hit the first of two, making it 95-94. Milwaukee came up with the ball after a scramble on the missed free throw and Pierce was forced to foul Brandon Jennings with 18.5 seconds left. Jennings hit both free throws.
The Celtics had trailed 88-81 with under a minute to play in regulation before Pierce scored five points, tying it on a 3 from the top with 2.5 seconds to play. Sanders airballed a foul-line jumper at the horn, sending the game to OT.
The basket came after a steal by Rondo after Terry missed a wide open 3 and Green batted the rebound out to Pierce.
Jennings' 3-pointer right in front of Boston's bench with 7:56 to play moved the Bucks ahead 74-72, their first lead since the game's opening basket. Boston tied it on Green's two free throws on the ensuing possession, but Milwaukee scored seven of the next nine, making it 81-76 on Sanders' left-handed hook with 4:39 to play.
Pierce's 3-pointer from the left wing -- after he let two defenders go flying by -- cut it to 83-81 with 2:45 to go. After he got a steal on the other end, he back-rimmed a 3 before the Bucks had a 24-second violation, giving the ball back to Boston with 1:46 left.
But Pierce's jumper rolled out on the next possession and Ellis hit a driving floater from the right side of the lane, making it 85-81 with 1:11 to go.
Sanders then had an alley-oop off Ellis' pass to give the Bucks a six-point edge with just under a minute to play.
Coming off his hot shooting night in Wednesday's win over Cleveland, Pierce looked sharp early. He missed his initial shot then hit seven straight, scoring 17 points until missing a pair of open 3s late in the second quarter.
The Bucks' usual starting guards were in there despite suffering recent injuries. Jennings had twisted his right ankle during Wednesday's game in Memphis and Ellis missed the morning shootaround with a sore back. "We've got to have our guards in the game, so it's good they'll be able to go," Skiles said before the game. ... Rivers didn't feel either team had an advantage even though they've already met three times in a short time. "It's amazing," he said. "This is the fourth time. It's funny. I don't think any of the lineups have been the same on either team, so it's four new times every time we play them." ... The Celtics next play on Christmas Day in Brooklyn against the Nets, opening a four-game road trip that has them on the West Coast for the final three. ... Milwaukee hosts Cleveland on Saturday night, the opener of three straight at home.
Copyright by STATS LLC and The Associated Press
Next 5 Games
12/22 CLE 8:30pm 12/26 BKN 8:00pm 12/29 MIA 8:30pm 12/30 @DET 7:30pm 01/02 SA 8:00pm
From Elias: Larry Sanders: 17 points and 20 rebounds-- He's the first Bucks player with at least 17 points and at least 20 rebounds against the Celtics since Kareem Abdul-Jabbar had 22 points and 29 rebounds against the Celtics on February 5, 1975