The Toronto Blue Jays rookie was supposed to start Wednesday's matinee against the Miami Marlins at Rogers Centre, but the club called up right-hander Scott Copeland from triple-A Buffalo to act as a spot starter for the interleague series finale instead.
Munenori Kawasaki was sent back to the Bisons in the corresponding roster move.
"He's a little bit sore, overall soreness," Blue Jays manager John Gibbons said of Sanchez following Tuesday's 4-3 win over Miami. "We're looking at him. We can't take a chance so we'll back him off one turn through the rotation and he'll be fine — just a precautionary thing."
Sanchez is 5-4 with a 3.55 earned-run average. He has pitched 66 innings over 11 starts so far this season.
The 22-year-old right-hander threw a career-high eight innings last Friday in a win against the Houston Astros, giving up one earned run while not issuing a single walk.
Sanchez is expected to make his next start on June 16 against the Mets in New York.
"He's a hard-working guy when he's out there — there's zero finesse to him and he's chalking up some innings, so he's just got a little fatigue," Gibbons said. "We figure we can't afford to lose him so we'll back him off a start, let Copeland make a start and he'll be good to go in the next go round."
Copeland has appeared in two games with the big league club this year, giving up two hits in three scoreless innings. He's also walked two batters.