The shot gave Orlando a 91-90 lead, and for Anderson it was a great ending to a frustrating game. He was hounded at every turn by Bucks forward Ersan Ilyasova and hit only two of six shots before hitting what proved to be the winner.
"I was lucky as it was a wide-open look," he said. "You have to give credit to the guys underneath. They fought for it and got it to me."
Howard, who led the Magic with 28 points and 16 rebounds, said he was just trying to get his hand on the ball.
"I couldn't get the rebound so me and (Bucks forward Mike) Dunleavy tipped the ball," Howard said. "They left him open at the wrong time. He knocked it down and won us the game."
Howard said it was very difficult for the Magic to come from behind in all three games.
"It is very tough," Howard said. "Both teams played hard, but we were just able to close it out. We stayed with it and stayed together and got a good win."
Orlando coach Stan Van Gundy called the win "unbelievable."
"For that to happen three times in 10 days and be down in the fourth, it's incredible," he said. "I don't remember ever having that in a season against anybody when three games sort of go so similarly."
Brandon Jennings led the Bucks with 22 points and Dunleavy added 18. Ilyaosova, coming off a 29-point, 25-rebound effort Sunday against New Jersey, had 11 points and 10 rebounds.
It was the Bucks' sixth straight loss at home, the first time Milwaukee has lost six in a row at the Bradley Center since a seven-game slide from Feb. 5-25, 2000.
Jennings said the Bucks always seem "to be a rebound away" from beating the Magic.
"We had to get that loose ball and they got it back and Anderson got a good look," he said. "It's really tough. We should have won the first time. We should have beat them in Orlando and we should have won tonight."
Orlando scored the first eight points of the fourth quarter to take a 75-70 lead with 10 minutes remaining as Howard scored on a dunk. But the Bucks then went on a 14-4 run to grab a 84-79 lead when Jennings hit a jumper with 4:33 remaining. Jennings had six points during the run.
J.J. Redick hit a jumper from the top of the key to give Orlando an 87-86 lead with 1:38 remaining. Larry Sanders followed with a layup to put the Bucks ahead 88-87 with 1 minute to go. Howard was fouled and hit one of two free throws to tie it with 46 seconds left.
Jennings hit a driving layup with 31.2 seconds left to put the Bucks back in front 90-88 before Ryan Anderson hit a 3-pointer with 18.1 seconds remaining to put Orlando up 91-90.
Nelson was fouled with 10.8 seconds to go and hit both free throws for the final margin.
Magic guard Jason Richardson missed his second straight game with a chest virus. For the Bucks, center Drew Gooden missed his third straight game with a right wrist sprain and rookie forward Tobias Harris missed his second straight game with a right shoulder contusion.Orlando guard Quentin Richardson left the game in the second quarter after taking a knee to his left thigh. He did not return to the game.