Williams scored 32 points and led a fourth quarter rally to help the Bucks snap a three-game losing streak with a 102-97 victory over the Grizzlies on Tuesday night.
"We really needed to get some guys shooting, and Mo was really on a mission," Bucks coach Larry Krystkowiak said. "He really got it revved up and got his flow going."
Williams, who was 14-of-22 from the field, scored all 10 Milwaukee points as the Bucks overcame a five-point deficit in the final 2 minutes.
"I had one thing on my mind, just to play," Williams said. "I play my best when I let my instincts take over."
Memphis was down 100-97 when Rudy Gay's 3-pointer bounced off the rim with 8 seconds left. Mike Miller's 3-pointer as time ran out also was off the mark, sending the Grizzlies to their fourth straight loss.
"I had a perfect look at it," Gay said of the shot that would have tied the game. "Usually I would knock it down, but not today."
Miller led Memphis with season-high 32 points, while Gay contributed 21 and six assists. Darko Milicic had 11 points and 12 rebounds, his third-straight double-double.
The Bucks were without two of their key pieces -- leading scorer Michael Redd, who is still suffering from a left knee strain, and Yi Jianlian, who injured his right shoulder in the Bucks' 91-83 loss to the Houston Rockets on Saturday.
But Williams, who also had seven assists, took care of Milwaukee down the stretch, scoring 12 of the Bucks final 14 points to overcome the Memphis lead.
"We should have trapped him earlier," Memphis coach Marc Iavaroni said. "We should have gotten the ball out of his hands earlier. That was my mistake. He did a good job down the stretch."
Memphis, which shot well early, finished the night hitting 47 percent, while the Bucks shot 48 percent. The Bucks held a 48-35 advantage on the boards, which contributed to Milwaukee outscoring the Grizzlies 15-2 in second chance points.
"They got a lot of offensive rebounds," Miller said of the Bucks 15 offensive boards. "Defense can only stop them so many times."
The Grizzlies also were in transition as Kwame Brown, Javaris Crittenton and Jason Collins, obtained in recent trades, were in uniform. Brown had four points and four rebounds in just under 16 minutes, while Crittenton finished with five points in almost 8 minutes.
"I thought they came in and gave a good effort," Iavaroni said. "Obviously, they are still getting their legs. A couple of mistakes here and there."
The Grizzlies hit their first eight shots to build an early 19-8 lead, their biggest of the game. Miller and Gay combined for 23 of the Grizzlies' 31 points in the period.
"We can't come out of the locker room and allow a team to make their first eight shots, no matter who we're playing," Krystkowiak said.
The Bucks answered with six points each from Villanueva and Bell in the second, but Memphis carried a 54-50 lead into the break behind Miller's 21 points and 11 from Gay.
Williams led the Bucks with 11 points, while Bell and Villanueva added 10 apiece.
The Grizzlies fell into one of their old habits by coming out stale to start the second half as the Bucks opened with an 8-3 run, capped by Villanueva's dunk to give Milwaukee its first lead at 58-57.
The two teams exchanged the lead through the third and were tied at 71 before the Bucks closed the quarter with a 7-2 spurt to carry a 78-73 lead into the fourth.
Memphis F Hakim Warrick got his first start of the season. ... Memphis rookie G Mike Conley did not play for the fifth straight game because of a chest contusion, but has returned to practice. He did not dress even though he was on the team's active list for the game. ... Brown entered the game with after about five minutes as Milicic picked up his second foul. Crittenton entered with just under 8 minutes left in the half. ... The crowd was sparse even by Memphis standards because of tornadoes and storms that hit the Memphis area about two hours before game time. The announced crowd of 10,749 referred to the number of tickets sold. ...Villanueva's double-double was his second of the season.