The lefty will be seeking the third win for the Orioles in a four-game set with the White Sox at Camden Yards after taking the first two games.
Saunders, who is 6-10 with a 4.22 ERA this season, is seemingly at home with Baltimore having grown up in Virginia as an Orioles fan.
The Orioles, winners of four straight, are hoping he can recover from a pair of rough starts that resulted in losses in the conclusion of his time with the D-backs. In the more recent of the two, Saunders fell to the Marlins on Aug. 20 after surrendering nine runs in 3 2/3 innings on 12 hits, including a pair of homers.
Dylan Axelrod, fresh from being called up from Triple-A Charlotte because of Gavin Floyd's injury, will be taking the mound opposite Saunders.
"I'm looking forward to another opportunity," Axelrod said. "I know we're in the thick of it here, in the race. I [want to] try to contribute."
In two stints in the Majors this season, the righty has appeared in 10 games (six starts) with a 1-2 record and 5.63 ERA. In his most recent start with the White Sox on July 21, Axelrod didn't factor into the decision in a loss to the Red Sox, throwing 6 2/3 innings of one-run baseball on seven hits with eight strikeouts.
In five starts with Charlotte since being sent back down, he's gone 2-1 with a 2.17 ERA.
"[Axelrod] has proven he can pitch, so it's a good choice," White Sox manager Robin Ventura said.
White Sox: Floyd sent to disabled list
Chicago placed Floyd on the 15-day disabled list retroactive to Monday because of a right elbow flexor strain.
The righty was taken out after two innings in his last start Sunday against Seattle. This is the second trip to the disabled list this season for Floyd, who was previously on it in July because of elbow tendinitis.
In 24 starts, Floyd is 9-9 with a 4.55 ERA.
Orioles: Wolf close to finalizing deal
The Orioles desperately needed left-handed help in its bullpen, and Randy Wolf, who was en route to Baltimore to sign a contract, may be the answer.
Manager Buck Showalter didn't rule out using Wolf as a starter, but with the already-full rotation, Wolf would figure to be a more likely candidate to be used in a relief role.
Wolf last played with the Brewers, who released him Aug. 22. He started 24 games for Milwaukee this season, going 3-10 with a 5.69 ERA.
"We are going to take one step at a time and get him here," Showalter said. "I know there was some competition for his services. And he's coveted and right now he finds us a place that he would be interested in. And I don't have to remind anybody that that hasn't always been the case."
White Sox outfielder Alejandro De Aza was sent to Triple-A Charlotte on Tuesday to begin a rehab assignment.
Orioles pitcher Jason Hammel is scheduled to throw five innings for Class A Frederick on Saturday in what may be his only rehab start.