Contreras allowed seven runs and eight hits in 2 2-3 innings in a 16-3 loss to the New York Yankees last night (Tuesday). He has lost his last seven starts and nine of his last 10.
Manager Ozzie Guillen says the team is making the move for the good of Contreras.
Gavin Floyd will start Sunday against Detroit, and Contreras will be used out of the bullpen. Guillen says the plan is for Contreras to miss one turn, but that may change if Floyd pitches well.
Contreras is 5-14 with a 6.60 ERA in 21 starts this season after going 13-9 with a 4.27 ERA last year.