The club announced that De Aza will report this afternoon, which necessitated a corresponding roster move. Left-hander T.J. McFarland was optioned to short-season Single-A Aberden, where he can join catcher Steve Clevenger.
They can share a ride back to Baltimore on Tuesday.
De Aza missed his flight early this morning, but he should be available during the game. Orioles manager Buck Showalter had to decide whether to keep him as an option off the bench or wait until Monday and perhaps insert him into the lineup.
De Aza, 30, batted .243/.309/.354 (96-for-395) with five home runs, 31 RBIs and 15 stolen bases in 122 games for the White Sox. He's hitting .276 against right-handers and .105 vs. lefties.
McFarland, 25, is 4-2 with a 3.10 ERA in 30 games (one start) for the Orioles.
Brad Brach will be the long reliever today if Wei-Yin Chen has an abbreviated start.