The left-hander missed 15 games with inflammation in his left hip and will be monitored closely from the dugout as he makes his first appearance on the hill since April 8 at Tampa Bay.
"We're just going to see how he's throwing, see how his control is," manager John McLaren said. "His arm's in pretty good shape, so if he throws strikes, hopefully he'll get deeper in the game. That's the key -- throwing strikes and keeping his pitch count down."
Bedard will be asked to be a stopper for a Seattle club that has lost three straight games on its current six-game homestand. Each loss has been by one run, dropping the team's record to 1-7 in games decided by a single run.
"We're letting some opportunities get by," McLaren said. "We just have to do a better job in a lot of phases of the game."
The losing stretch has prompted the Seattle manager to juggle the lineup, inserting Greg Norton in the designated hitter spot in place of the struggling Jose Vidro. Norton has three hits in eight at-bats this year, while Vidro is batting .195 (17-for-87) with two home runs and 16 RBIs on the young season.
"I want to keep Norton in the mix," McLaren explained before Saturday's game against the A's. "We need to get some guys going. We're a month into the season now, we've gone far enough giving everybody an opportunity. This game's about winning, and that's what I'm going to tell [the players]. We're not in bad position, but we should be in much better."
"We're not running on all cylinders right now," outfielder Raul Ibanez said of the team's start to the season. "We're going to have a bunch of guys get hot at the same time and things are definitely going to turn around."
Bedard, acquired by Seattle in an offseason trade that sent top prospect Adam Jones, reliever George Sherrill and three other prospects to Baltimore, has made a pair of starts for the Mariners, posting a 1-0 record with a 3.27 ERA.
To make room for Bedard on the roster, the Mariners optioned right-hander reliever Roy Corcoran to Triple-A Tacoma. Corcoran worked 10 2/3 innings for the Mariners, allowing two runs on eight hits while holding opposing hitters to a .211 batting average.
Chris Hester is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.