O.J. Mayo scored 22 points and came face-to-face with Carmelo Anthony on the baseline after the Knicks star was whistled for an offensive foul in the second quarter. The scorers went at it for several minutes up and down the court after Anthony was earlier called for traveling while guarded by Mayo.
Anthony led New York (2-4) with 22 points.
Beno Udrih's straightaway 3 with 6:25 left tied the game at 87 after the Knicks trailed by 18 points in the third quarter.
Butler's 3 with the shot clock expiring gave Milwaukee (1-5) a five-point lead with 5 minutes left.
Butler was having so much fun, he even turned to Green Bay Packers quarterback Aaron Rodgers, sitting courtside, and mimicked Rodgers' trademark "championship belt" celebration after hitting a jumper.
The game was played at the Resch Center, just down the street from Lambeau Field.
The game was as chippy as a football game in a couple instances, too, especially when Mayo and Anthony had their up-close argument in the first half on the baseline.
But Anthony, as usual, was the catalyst. He was 8-for-23 shooting, and had nine rebounds and seven assists.
Neal's shooting and three rebounds in the closing minutes from Larry Sanders (seven points, seven rebounds) help seal coach Larry Drew's first preseason win since coming over from Atlanta.
It hasn't been an easy transition for Drew with so many injuries this month. Point guard Brandon Knight added to the woes after having to sit out Wednesday's game with a sore hamstring.
But Drew saw some good signs from shooting guard Neal, who had been slowed by a left foot injury.
Butler started 3 for 3 to open the third quarter, helping the Bucks to open up the 18-point lead. He is one of 11 new acquisitions for the re-made team.
Anthony did give Bucks' first-round draft pick Giannis Antetokounmpo a few "Welcome to the NBA" moments after drawing foul shots on a missed 3-pointer in the second quarter, then hitting a 3 at the buzzer to close out the third to get the Knicks within 77-72.
A pumped Anthony stomped back to his bench, pointing his right index finger to the side of his head.
Knicks PG Raymond Felton sat out again with a sore left hamstring. ... Besides Rodgers, other Packers sitting courtside included injured receiver Randall Cobb, guard Josh Sitton and defensive lineman Johnny Jolly.