The loss snapped the Orioles' season-best, five-game winning streak.
Holland, who logged his 25th save in 27 chances, gave up a leadoff single in the ninth to Nick Markakis and a run-producing triple to Adam Jones with none out.
Holland preserved the victory by striking out Chris Davis, and retiring J.J. Hardy and Henry Urrutia on grounders.
Chen (4-0), who was making just his second start after replacing Luis Mendoza in the rotation, limited the Orioles to three hits and one run, retiring the final 10 batters he faced.
This material may not be published, broadcast, rewritten, or redistributed.