Lefty Wei-Yin Chen was originally scheduled to make the start, but with Detroit's mostly right-handed-hitting lineup, Baltimore opted to give him an extra day's rest.
"It kind of fits best for our club and the needs, some of the situations that have changed over the past couple days that we need to be prepared for down the road," Orioles manager Buck Showalter said of the move to promote the righty Gausman and skip Miguel Gonzalez in the rotation.
"Obviously some guys pitch better with extra rest, some guys don't. Kevin, because of some of his inactivity down and the way they've shortened him up, his inning-management is in good shape right now as we sit here in the middle of May."
That inactivity was due to pneumonia, as Gasuman was on the Minor League disabled list -- the team thought it was an oblique injury -- and he returned Saturday with no issues in a 77-pitch outing for Triple-A Norfolk. Gausman has faced the Tigers before, allowing one run and five hits in six innings at Camden Yards last June 2.
"I've felt for a while that I could go 90-100 pitches," said Gausman, who found out about the promotion on Monday night and drove from Norfolk on Tuesday morning. "I feel good physically. And more than anything, that's probably most important. I think part of the reason I was kind of held back a little bit was because I was just coming off the DL. They wanted to make sure everything was OK."
Gausman, No. 29 on MLB.com's Top 100 prospects list, seemed to find his footing in the bullpen after a rocky time as a starter in 2013. His last outing with the O's came in relief on Sept. 28, when he tossed 1 1/3 scoreless innings, striking out two. His most recent MLB start was June 13 against the Red Sox, when he allowed two runs on six hits over 5 1/3 innings.
Of his season so far, Gausman admitted it's been kind of crazy.
"I started the season sick and had to grind through two starts where I wasn't feeling good," he said. "But that's part of being a starting pitcher.
"More than anything, I feel good. I feel good about all my pitches. It was just good to get out there, especially after being on the DL. That was my first time on the DL. Kind of frustrating to be around baseball all day and not play. So, definitely a little frustrating [this season], but obviously just happy to be here."
Brittany Ghiroli is a reporter for MLB.com. Read her blog, Britt's Bird Watch, and follow her on Facebook and Twitter @britt_ghiroli. This story was not subject to the approval of Major League Baseball or its clubs.