Jake Peavy was scratched from Thursday's series finale against the Rangers with back spasms and replaced by Hector Santiago.

Santiago, who was scheduled to make his first start of the season Friday night in Kansas City, will still be pitching on regular rest after throwing 86 pitches in relief of Gavin Floyd last Saturday night at home against the Rays. Floyd left the game with what was diagnosed as a right flexor strain, and he was placed on the disabled list Sunday.

According to White Sox general manager Rick Hahn, via email on Thursday, Floyd is in the process of following up with various doctors so the White Sox and Floyd have multiple options on his prognosis.

"We hope to have a treatment plan next week," Hahn wrote in the email.

This trip to the disabled list marks Floyd's third since early July of last season for issues in the same general area. From July 8-23, Floyd was out of action with right elbow tendinitis. He then returned to the DL from Aug. 27 to Sept. 12 with the same flexor strain he has been diagnosed with presently.

An MRI taken on Floyd on Saturday night showed no structural damage. It also showed the flexor strain to be in a different spot from last year, according to Floyd.

Peavy has a 3-1 record with a 3.38 ERA over five starts this season. He has fanned 39 and walked six over 32 innings and is coming off of a win over the Rays.

In 2012, Santiago posted a 2-0 record with a 1.86 ERA over four starts.

The White Sox already have six players on the disabled list, including two starting pitchers in Floyd and John Danks.