The 51s, with Los Angeles Dodgers pitcher Brad Penny making a rehabilitation start, lost to the Oklahoma RedHawks 4-3 Saturday in a Pacific Coast League game in Oklahoma City.
Penny allowed two runs on six hits and a walk in four innings, with four strikeouts, and he left with Las Vegas trailing, 2-1.
The 30-year-old right-hander, coming back from shoulder troubles, is set to rejoin the Dodgers on Monday.
The 51s (61-54) took a 3-2 lead on Xavier Paul’s two-run homer in the sixth inning, but the RedHawks (63-52) scored once in the seventh and once in the eighth.
Mitch Jones homered in the second for Las Vegas.