Playing without their star guard and leading scorer, the Hawks never trailed and rolled to an 99-83 victory over the Cleveland Cavaliers on Sunday night.
"I got going early and my teammates kept coming to me," Williams said. "I had a big night and our team had a big night."
Johnson, who averages 18.5 points, sprained his right thumb Saturday, but the Hawks didn't need him to beat the Cavaliers, who have the worst record in the NBA.
Williams shot 9 of 14 from the field, including three 3-pointers, and 8 of 9 from the foul line in 43 minutes.
"Marv looked very confident out there," Horford said. "He really just took what the defense gave him and he was being aggressive and attacking the rim. I think when he plays at that level, not necessarily scoring [31 points], but just being aggressive like that, I think we really are a different team."
Johnson missed two weeks earlier in the season with an elbow injury, so Williams and his teammates are familiar with taking on added responsibility.
"It was something we had to learn to do," Williams said "The guy doesn't miss many games. We knew what we had to do. Everyone had to chip in a little more."
Coach Larry Drew isn't sure how long Johnson will be out. X-rays taken Saturday were negative, but Johnson didn't travel with the team to Cleveland.
Horford was 10 of 15 from the field and had 10 rebounds, while Josh Smith scored 13 points and had a season-high 18 rebounds.
The Hawks, who clinched a playoff spot in the Eastern Conference by beating New Jersey on Saturday, lost eight of 11 before winning the last two.
"I thought we really played well together," Drew. "I thought we really shared the basketball. We really did a good job moving the basketball."
For Cavaliers coach Byron Scott, the game was a repeat of the same bad movie he's been watching most of the season.
"We got off to a bad start," he said. "We didn't come out with the energy and aggressiveness we needed to come out with, for whatever reason."
Atlanta scored the first eight points and led by as many as 11 in the first quarter. Atlanta was ahead 52-39 at halftime and built the lead to 19 in the fourth quarter.
The Cavaliers missed their first eight shots and didn't score until J.J. Hickson put in an offensive rebound at the 6:50 mark.
Forward Samardo Samuels, who scored nine points in 22 minutes, left the game in the second half with a sprained right wrist. X-rays were negative.
Cleveland, which beat Detroit on Friday, hasn't won back-to-back games since winning three straight Nov. 5-9. The Cavaliers host Miami on Tuesday night, marking LeBron James' second game in Cleveland since signing with the Heat in July. James was greeted with a hostile reception when he returned on Dec. 2, but the Heat routed the Cavaliers 118-90.
Hinrich took some good-natured ribbing from his teammates before the game after Kansas, his alma mater, was upset by VCU in the NCAA Tournament. ... Scott hopes C Semih Erden (right adductor strain) will play again before the season ends. Erden has appeared in one game since being acquired from Boston last month. ... Hall of Fame radio announcer Joe Tait worked his first game of the season Sunday. He had heart surgery in January.
DeMar DeRozan, arguably the top shooting guard who could hit the free-agent market, is focused on re-signing with the Raptors, a source said.
Cavaliers point guard Kyrie Irving has accepted an invitation to play for Team USA at the Summer Games, filling out the 12-man roster for Rio de Janeiro.
Heat president Pat Riley said re-signing Whiteside will be the team's No. 1 priority, with a max contract projected to be $94.8 million over four years.