"I came here yesterday and just worked on making layups, making layups, making layups, because those are big shots for me," Williams said.
Williams scored 10 points in the fourth quarter and Redd added eight. The Bucks shot 68 percent in the final period and outscored the Spurs 31-20.
The effectiveness that Williams and Redd showed in getting to the basket for layups contributed to Milwaukee having a 76-40 advantage in points in the paint.
The dominance came mostly out of the half-court offense because San Antonio had a 18-15 advantage in fast-break points.
Milwaukee also struggled from outside, going 1-of-11 from 3-point range.
"To score that many points in the paint against a team like San Antonio is remarkable," Bucks coach Terry Stotts said.
The Bucks (14-14) returned to .500 for the first time since they were 2-2 on Nov. 6. Redd was 14-of-22 from the floor and made all eight of his free throws as Milwaukee won in San Antonio for the first time in five years.
The Spurs (21-8) had won six of seven. But coach Gregg Popovich doesn't think the won-loss record has been built by defense -- as it usually is in San Antonio.
"They scored enough points to win three games," Popovich said. "This is our worst defensive team in the last seven to eight years.
"Our players need to make up their minds ... that (defense) is what wins games for us, or if they want to make summer plans."
"They obviously missed those guys," Redd said. "But they're capable of beating anybody regardless of who is playing. They almost won tonight."
It looked like Tony Parker would take up the slack. He scored 24 points, but only two in the second half.
Tim Duncan had 25 for San Antonio.
"Things that hurt us in the first half we were able to shore up in the second half -- mainly Parker's penetration," Stotts said.
Trailing by 13 in the third quarter, the Bucks took the lead when Bogut rebounded a miss by Redd and made the basket with 5:32 left in the game.
The Bucks were ahead by two when they got a layup from Williams and made it 110-104 with 1:22 to go when Patterson rebounded Redd's miss and passed the ball back out to Redd for a jumper.
Watching Williams' layup and the 76-point explosion in the paint by the Bucks irked Duncan.
"That's never happened -- not since I've been here," Duncan said. "Defense obviously is a concern of ours right now."
The Spurs outscored Milwaukee 17-6 over a span of 5:26 to take a 13-point lead midway through the third quarter. When Bruce Bowen hit his second of three 3-point shots in the third quarter, San Antonio led 78-65.
But the Bucks ended the quarter by outscoring the Spurs 14-2 over a span of 3:25, and Milwaukee trailed by 84-83 with less than a minute before the fourth quarter.
Redd hit 6-of-7 to start the game. He took just two shots -- making them both -- in the second quarter when the Bucks fell behind by as many as eight with three minutes to go. San Antonio led 61-55 at halftime.
Parker hit 4-of-5 to start the game.
The Bucks shot 14-of-22 from the floor for 64 percent during the first quarter and built an eight-point lead 6:11 into the game, but they still trailed 33-31 heading into the second quarter. Redd missed his first shot of the night and made six straight before the start of the second.
- Bucks guard Steve Blake played only seven minutes in the first half before he came out of the game with a lumbar strain.
- The Bucks hadn't won in San Antonio since Dec. 23, 2001.
- Bogut was called for a technical foul early in the second half for arguing a call with referee Violet Palmer.
- Spurs reserve center Fabricio Oberto was 4-for-4 from the floor, which still fell far short of his team record 11-of-11 night on Nov. 8 against Phoenix.