Sheets will be tasked with extending Atlanta's six-game winning streak in his debut with the club, which will come at Turner Field against the Mets in the finale of a three-game series. Johan Santana, also no stranger to the comeback trail, will start for New York, which has dropped three straight and four of five.
Atlanta is 2 1/2 games ahead of New York and in second place in the National League East, behind Washington.
Sheets, 33, is a four-time All-Star who went 53-44 with a 3.24 ERA and more than five strikeouts per walk with the Brewers from 2004 to 2008. He missed the entire 2009 season due to injury before posting a 4.53 ERA in 20 starts for the A's in 2010, making his final appearance on July 19.
Sheets, who has now overcome a second Tommy John surgery, signed a Minor League deal with the Braves on July 1, then gave up six earned runs in 10 2/3 innings with Double-A Mississippi, although he struck out 10 and walked just one.
"I thought I threw the ball pretty well, to tell you the truth," Sheets said after a bullpen session at Turner Field on Thursday. "Mistakes got hit, like they will up here. Even when you're in midseason form, you make mistakes -- it's going to happen. You try to minimize them and make pitches around them."
Sheets threw 89 pitches in his final start with Mississippi, and manager Fredi Gonzalez said the right-hander will be on a pitch count that could be as low as the high 80s. With a day off on Monday, the bullpen should be ready to cover for a short outing.
Santana has rebounded well after missing the 2011 season following surgery on his shoulder, but he tied a career high by allowing 13 hits in his previous start, on July 6 against the Cubs. He gave up seven earned runs in 4 2/3 innings that day and also sustained a mild sprain in his right ankle that caused his first start of the second half to be pushed back from Friday.
"I told these guys I would have pitched [on Friday], but the doctor told us that they want me to take an extra couple of days and just give it a break," Santana said. "It was sore the day after, but it was manageable."
The lefty's last outing against the Braves also was an unpleasant one. On April 17 at Turner Field, he lasted a career-low 1 1/3 innings, giving up six runs, four earned.
Mets: Time off for Duda
Right fielder Lucas Duda didn't start on Saturday because of a strained left hamstring, and manager Terry Collins said he likely would be out of the lineup for a few days.
Duda said that the hamstring has been bothering him for a few weeks, and he is hitting .137 with one extra-base hit in his last 15 games. That includes a game-ending strikeout in a pinch-hitting appearance on Saturday.
"I just said, 'Look, we've got to get your leg right,'" Collins said. "Because if your leg is affecting your hitting, if it's affecting your trunk rotation and everything else, than it's got to get fixed."
Kirk Nieuwenhuis started in right field on Saturday, with Jordany Valdespin getting the nod in left.
Third baseman David Wright entered Saturday with an eight-game hitting streak and a Major League-best .395 road batting average but went 0-for-5 with four strikeouts and four runners left on base.
Braves: New shortstop on the way
Martin Prado made an emergency start at shortstop on Saturday, but Atlanta should have a more suitable fill-in at the position on Sunday.
In the middle of Saturday's game, the Braves acquired Paul Janish from the Reds in exchange for Minor League pitcher Todd Redmond. With Andrelton Simmons out for at least six weeks with a fractured right pinky and veteran Jack Wilson on the 15-day disabled list with a dislocated right pinky, Janish likely will step right into the lineup.
Janish, 29, has a .722 OPS at Triple-A Louisville this season and a .591 mark in 975 Major League plate appearances, but he is known for his solid defense.
"In evaluating after Simmons was hurt, and talking with our scouts, we thought Janish was the best defensive shortstop out there that we could acquire," general manager Frank Wren said. "He was the No. 1 guy on our list."
First baseman Freddie Freeman went 3-for-4 with a two-run double on Saturday and is 11-for-22 with three doubles and a home run over his past six games.
The Braves' Matt Diaz is 18-for-35 in his career against Santana, while Dan Uggla is 1-for-21.
Coincidentally, Santana also started the last time Sheets faced the Mets, back on Sept. 1, 2008, in Milwaukee. Sheets threw five scoreless innings and left with a lead, but Eric Gagne blew the save in a 4-2 Mets victory.