Sheets, who is 10-4 with a 3.39 ERA, was coming off a scoreless inning of work at Tuesday's All-Star Game in San Francisco and retired nine of the first 10 Rockies hitters he faced on Saturday night. Ryan Spilborghs put Colorado on the board with a two-out solo home run in the third inning, but Sheets escaped further damage and then struck out Garrett Atkins leading off the fourth.
That brought up Todd Helton, who should have been retired on a foul popup that was dropped by Brewers catcher Johnny Estrada for the team's second error. It was one of four consecutive foul balls off Helton's bat, and after the fourth, manager Ned Yost and assistant athletic trainer Dan Wright joined Sheets on the mound.
"Something happened on the last pitch," Sheets said. "I felt something pop, snap. I don't know what it was. But I knew, when the trainer got out there and tested it, that there weren't going to be any more pitches today."
Yost had that same feeling when he walked to the mound.
"I knew something was wrong," Yost said. "I thought it might be a blister or something. I didn't know what it was. But of all the things I can think of happening, this is probably the best-case scenario. We'll see how he feels [Sunday]."
Sheets and the team's athletic training staff made two similar decisions earlier this season to call it a day before an injury worsened. On April 25 at Wrigley Field, Sheets left a start against the Cubs after three innings with a groin strain, and made his next start six days later as scheduled.
Then, on May 22 at Los Angeles, Sheets exited in the middle of the seventh inning when he felt the beginnings of a blister on his middle finger. Seven days later, after one extra day off, Sheets beat the Braves and began a six-game winning streak that essentially landed him his All-Star spot.
Sheets' teammates were hoping for a similarly quick recovery.
"He's our ace," said infielder Tony Graffanino, who delivered a game-winning, pinch-hit bloop single in the 10th. "You definitely want to have your ace in the last couple months of the season."
Especially because the rest of Milwaukee's rotation has been struggling. They have one quality start -- defined as six or more innings with three or fewer earned runs -- in the team's last 11 games. Brewers starters are 2-5 with a 6.21 ERA in that span.
Should Sheets miss a start, right-hander Yovani Gallardo would slide into that spot in the rotation. Gallardo pitched 4 2/3 innings of scoreless, one-hit relief on Saturday night and is 1-0 with a 2.79 ERA in his three Brewers starts.
The Brewers shifted Gallardo to the bullpen after his June 29 start to limit the 21-year-old's innings.
"We want to keep him in the rotation because he's a great pitcher," Gallardo said of Sheets. "Hopefully, it's nothing serious. We'll just see what happens."
Is Sheets worried?
"It ain't that you're worried, but that's something that you need to work with, your hand," Sheets said. "I'm optimistic. I think I'll be all right, personally. Today I wasn't."
The Brewers' win -- just their fourth in the last 12 games -- helped to boost the right-hander's spirits.
"Huge win," Sheets said. "It's no secret."