Bochy emphasized that Casilla, who blew his fourth save opportunity in 24 chances Wednesday night when Justin Bour hit a three-run, ninth-inning homer to give Miami a 6-5 victory, wasn't injured.
"There's no pain," Bochy said.
Bochy named Sergio Romo and Javier Lopez as possible closers in Casilla's absence.
Casilla, who's 4-2 with a 3.03 ERA, has struck out 30 batters in 29 2/3 innings and has limited opponents to a .250 batting average. However, left-handed batters -- such as Bour -- have hit .326 off him, compared to .197 for righties.
Chris Haft is a reporter for MLB.com. Read his blog, Haft-Baked Ideas, follow him on Twitter at @sfgiantsbeat and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.