Gausman, acquired by Atlanta at the non-waiver trade deadline, has also never faced the Milwaukee Brewers before in his six-year major league career.
The Braves (62-50) and Brewers (66-52) open a three-game weekend series in Atlanta with each second-place team trying to chase down the leaders in their respective divisions.
The Braves trail Philadelphia by one game in the National League East coming into the start of an 11-game homestand, while the Brewers are two games back of the Chicago Cubs as they begin an eight-game road trip.
Gausman will be opposed by rookie right-hander Freddy Peralta, who recorded one of the Brewers' three victory in a four-game series with the Braves in Milwaukee on July 5-8.
Gausman, the fourth overall pick in the 2012 draft, didn't live up to expectations in Baltimore, but the Braves feel that the potential his still there despite just a so-so debut during a loss to the Mets in New York last weekend.
"I just think, overall, our system is going to be good for him," manager Brian Snitker said. "I don't think we're going to reinvent him, because he's got too good of stuff. I just think what we have here is going to help him."
Gausman, who was 5-8 with a 4.43 ERA in 21 starts for Baltimore this season, gave up six hits and three runs over five innings in the Braves' shutout loss to the Mets last Saturday during a 5-3 road trip. He struck out two, walked two and hit a batter.
The 27-year-old Gausman admitted afterwards that he was "more nervous than I was for my (major league) debut. But I tried to calm myself down and remember that it was just another game."
Gausman's fastball can reach 100 mph and he throws his four-seamer more than 50 percent of the time. But batters hit .335 against it this season with the Orioles.
The Braves want Gausman to modify where and when he throws his fastball, with better results especially hoped for on the first pitch to each batter.
Peralta, who is 5-3 with a 3.54 ERA in 10 games, beat Atlanta in his sixth career start on July 6 in Milwaukee, allowing three hits and a run over six innings. The 22-year-old native of the Dominican Republic struck out six and walked three.
Peralta allowed 11 runs over 13 2/3 innings in his last three starts of July, but defeated Colorado in his most recent outing.
Peralta needed 31 pitches in the first inning, but allowed just two hits and two runs over six innings after being handed a six-run lead in the bottom of the inning. He struck out eight and walked two in the 8-4 victory that was part of the Rockies' 3-3 homestand.
"I've been working hard the last couple of starts," Peralta said afterwards. "It's something that's going to take time, but I'm making adjustments."
"Once Freddy locked into his delivery after the first inning, he was excellent," Brewers manager Craig Counsell said.
The Rockies became the first team Peralta has faced twice. He made his debut against Colorado on May 13 at Coors Field and struck out 13 over 5 2/3 scoreless innings.
Peralta has fanned 71 in 53 1/3 innings. He's also walked 28, but allowed just 27 hits.