Chicago White Sox right-hander Jake Peavy has been scratched from Thursday night's start against the Texas Rangers because of back spasms.
Left-hander Hector Santiago will make his first start of the season in Peavy's place. Right-hander Justin Grimm is starting for the Rangers.
Peavy is 3-1 with a 3.38 ERA and tied for the team lead in wins with Chris Sale, who beat Texas on Wednesday night. Peavy has 39 strikeouts in 32 innings.
Peavy missed half of the 2010 season after right shoulder surgery but hasn't been on the disabled list since June 2011.
Santiago is 0-1 with a 2.51 ERA in seven relief appearances this season. He made four starts last year.