The Marlins made the move before the start of a six-game trip in Colorado. The injury forced Sanchez from Thursday's game against Atlanta in the fifth inning.
Sanchez had shoulder surgery in June 2007 and returned last July. As a rookie in 2006 he went 10-3 and threw a no-hitter against Arizona, but he's 1-4 this season with an ERA of 5.79.
Marlins Manager Fredi Gonzalez said team officials initially feared one of four tacks used to stabilize Sanchez's shoulder had come loose and were relieved when doctors determined the surgical repair remained intact. Still, Gonzalez said Sanchez likely will be sidelined until after the All-Star break.
"It will be three to four weeks of no throwing and then he'll start [rehabbing]," Gonzalez said prior to Friday night's game at Colorado. "So you're going to be missing a pretty good pitcher for a while. You're talking two months probably by the time he gets going again."
Top infield prospect Chris Coghlan was recalled from Triple-A New Orleans, where he hit .344 in 25 games. Coghlan will be available to spell second baseman Dan Uggla and third baseman Emilio Bonifacio.
Gonzalez said Coghlan also will see duty in the outfield, which he hasn't played regularly since his Little League days, in an attempt to get his bat in the lineup consistently. The Marlins have been slumping offensively, hitting .229 as a team for the NL's second-lowest average.
"We're trying to inject a little offense into our lineup and this kid deserved an opportunity, the way he was swinging the bat in Triple-A," Gonzalez said. "If he hits, we'll play him someplace. We may have to live with a mistake in the field but we think we need the possibility of a good bat in the lineup."
Coghlan was penciled in to Friday night's lineup at second base. He's expected to start in left field on Sunday, Gonzalez said.
"I didn't want to bring this kid up -- and this is his first major league game ever -- and put him in left field. So, hopefully let him play second, his normal position, and get over the first-game jitters. Then, the plan is to run him out in the field."