Andrew Cashner suffered his fifth loss of the season after yielding six runs (four earned) in six innings against the Giants on Tuesday.
Josh Johnson (elbow) reported that he had felt tightness in his triceps after throwing a simulated game a week ago.
Austin Hedges will make his first major league start in Wednesday's game against the Giants.
Padres recalled LHP Frank Garces from Triple-A El Paso.
Padres placed RHP Brandon Morrow on the 15-day disabled list, retroactive to May 3, with right shoulder inflammation.
The Padres acquired the rights of catcher Yenier Bello from the Joplin Blasters of the independent American Association.
Tyson Ross was solid on Monday in a losing effort against the Giants, yielding two runs in seven innings.
Padres purchased the contract of C Austin Hedges from Triple-A El Paso.
Padres designated C Wil Nieves for assignment.
Joaquin Benoit (arm) threw a scoreless inning in his return to action Sunday against the Rockies.
Corey Brock of MLB.com reports that the Padres are expected to recall Austin Hedges from Triple-A El Paso on Monday.
Justin Upton swatted his seventh home run of the season and drove home three, powering the Padres to an 8-6 victory over the Rockies on Sunday.
James Shields served up three home runs against the Rockies on Sunday and still wound up with a victory despite allowing five runs on nine hits over his 5 1/3 innings.
Padres prospect Colin Rea put on a clinic Saturday for Double-A San Antonio, allowing just one hit over eight scoreless frames.
Padres manager Bud Black said Sunday that it's possible Joaquin Benoit (arm) could go on the disabled list.