Sheets allowed just two hits on Friday, walking none and striking out four, helping lift the Brewers to a 5-2 victory over Cincinnati before 32,629 fans.
Bill Hall hit a two-run home run, his sixth of the season. Craig Counsell and J.J. Hardy each had two hits for Milwaukee.
Sheets (4-0) said he began to feel the tightness after retiring Reds pitcher Bronson Arroyo to end the third inning. It got progressively worse, prompting Brewers manager Ned Yost to put in Rickie Weeks to pinch-hit for Sheets in the sixth.
With the victory, Sheets improved to 4-0 with a 3.00 ERA in five career starts at Great American Ball Park.
"It's April, you don't take any chances," Yost said. "It started to get stiff. He went out in the fourth, and it felt better. He could've continued. It got stiffer. I'm not taking any chances with Ben Sheets. I'm just not doing it."
Following the game, Sheets' right arm and shoulder were heavily iced and bandaged. He said he's been receiving daily treatment on his arm.
"We've been kind of treating it since the last start," Sheets said. "It's really sore. Kind of cramping in there. Last time, it got better every day. I'm cautiously optimistic about how it'll feel tomorrow."
Sheets showed no signs of the injury on the mound, retiring eight consecutive Reds batters before exiting.
"I know I could've continued," he said. "The third inning hurt worse than the fourth or fifth. I'm glad [Yost] made the decision. I thought I could've given us another inning. I'd rather be safe."
The Brewers handed Sheets an early lead on Prince Fielder's bases-loaded sacrifice fly in the first putting them ahead 1-0.
Corey Hart followed with an RBI single to center, scoring Hardy to make the score 2-0.
Prior to Friday's game, Yost said moving Hall to sixth in the batting order was "not a big deal".
Hall, who was batting just .091 on the road trip and had struggled in his career against Arroyo, was moved out of his customary fifth position in favor of Hart.
The move proved to be a major boost for Hall and the Brewers offense.
"He was due," said Yost. "He battled off some good pitches."
Hall connected on a 3-2 pitch and sent it sailing 439 feet into the second deck in left field to give the Brewers a 4-0 lead.
It was his second home run into the left-field bleachers at Great American Ball Park, and his first since a May 6, 2004, shot off Aaron Harang.
Hall was batting just .077 in his career against Arroyo.
"I guess 1-for-100 isn't too bad," Hall said. "Whether I have good at-bats or bad at-bats against him, it seems to result in an out. He strikes me out with a lot of pitches. I can't guess against him. I was looking for something out over the plate. I put a good swing on it."
Arroyo (0-2) allowed five runs, four earned, on eight hits in 5 2/3 innings.
Jason Kendall's RBI single in the sixth made the score 5-0.
The Reds attempted to rally in the eighth against left-hander Mitch Stetter, who was making his first appearance since being recalled Thursday from Triple-A Nashville.
Adam Dunn and Edwin Encarnacion walked. Pinch-hitter Ryan Freel singled to load the bases.
Stetter struck out Paul Bako and Scott Hatteberg, both swinging.
David Riske then got pinch-hitter Corey Patterson to fly to left fielder Ryan Braun to end the inning.
The Reds got on the board for the first time in the ninth, with Dunn's RBI single off Riske.
Riske allowed two earned runs on three hits in 2/3 innings.
Encarnacion's bloop single off Eric Gagne dropped over Fielder's head, scoring Phillips with the second run.
Gagne fanned Javier Valentin and Bako to end the game.
"I was glad the bullpen came in and shut them down," said Sheets. "They've had some short starts lately. My goal wasn't to leave after 60 pitches. I didn't want to do that to them."