Friday's start originally belonged to R.A. Dickey, but Toronto wanted to separate Brandon Morrow and Dustin McGowan in the rotation, so McGowan will now take the hill for the series opener in Baltimore.
The Orioles, who are coming off a 3-3 road trip to Detroit and New York, will catch their breath first during Thursday's off-day and hope that rest will be enough for ailing shortstop J.J. Hardy to return to the lineup.
Hardy has missed five of the last six games with back spasms, playing Saturday in Detroit only to leave on Sunday during batting practice after his back locked up in a different spot while taking ground balls. He will work out at Camden Yards on Thursday after he gets treatment.
"I feel like tomorrow I'll be able to go to the field, run around, do some stuff and really test it out and hopefully be ready to go [on Friday]," Hardy said. "We'll see how it feels. Hopefully tomorrow I'll be able to do everything and should be good to go. I feel good about it."
The Orioles have not set their pitching order just yet, although they figure to use a combination of Bud Norris, Chris Tillman and Ubaldo Jimenez in the three-game series.
McGowan, who will be pitching on seven days' rest, made the Blue Jays' rotation at the end of camp after an injury-plagued few years. The right-hander struggled in his season debut, against New York, giving up four runs on eight hits and a walk over 2 2/3 innings, and Toronto felt the main reason was that he was tipping his pitches.
Pitching coach Pete Walker picked up that McGowan was coming to a different set position with his glove depending on what pitch he was about to throw. Yankees outfielder Jacoby Ellsbury said he didn't see anything, but with so many others having noticed it, the New York dugout could have as well.
"It's tough sometimes on the fly to make adjustments like that," Blue Jays manager John Gibbons said. "He has never done that before; we've never seen that out of him. Sometimes they pick up little things every now and then. That makes it much easier to hit."
"They hit some balls hard, and there were also some ones that just found the holes, too," said McGowan, who said it was a draining day and that he may have thrown too many pitches in the bullpen warming up. "For me, I just [have to] learn to get the ball back down. It was up in the zone tonight, and when they're up they get hit hard.
"I have to fix that tipping thing for sure, because even I noticed after the first inning they were putting good swings on every pitch I threw, and I knew something was wrong from the get-go, too."
The Orioles will counter with right-hander Chris Tillman, who will be working on regular rest and leapfrogged Bud Norris with Thursday's off day. Tillman is coming off a dominant win Sunday in Detroit, in which he out-dueled Tigers ace Justin Verlander and tied a career-high 8 1/3 innings. He allowed one run on a solo homer as Tillman continues to establish himself as the O's ace.
Blue Jays: Wagner added to bullpen
The Blue Jays added some depth to the middle-relief section of their bullpen by recalling right-hander Neil Wagner from Triple-A Buffalo prior to Wednesday night's game against the Astros.
To make room on the 25-man roster, the Blue Jays optioned right-hander Marcus Walden to Buffalo. Walden had his contract selected on Saturday did not appear in a game.
Toronto has been short a reliable middle reliever since the start of the season, when closer Casey Janssen was placed on the 15-day disabled list. The Blue Jays still have Sergio Santos and Steve Delabar at the back end of their bullpen, but there was a need for another quality arm.
Wagner should help fill the void. He is coming off a 2013 season in which he gained his manager's trust by posting a 3.79 ERA in 38 innings.
"He came into his own, he started out in Triple-A and put it all together," Gibbons said. "Came up and did a nice job for us. He has that big arm, that's what you like to see coming late into a game. The key for him is, he started finding that strike zone consistently. That's something that had been deserting him in his career until last year. We expect him to fill a big role for us."
Orioles: Lough returns after concussion tests
Outfielder David Lough left the team on Tuesday to see two doctors in Baltimore on Wednesday morning, returning in time for the game against the Yankees after passing some concussion tests.
"It's been a lingering thing, just kind of playing through it, but they could tell I wasn't right out there," said Lough, who dealt with concussion-like symptoms during Spring Training. "I didn't feel right, so I spoke up and said something. And they said I needed to go run some tests, and everything is fine now."
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.