The Rays designated Guerra for assignment Wednesday.
Guerra's latest stint with the Rays lasted just under two weeks, with the right-hander making a trio of two-inning relief appearances during that stretch and allowing three earned runs on three hits and four walks. The Rays called up Calvin Faucher from Triple-A Durham to replace Guerra in the bullpen and on the 26-man active roster. Guerra will now be exposed to waivers but could remain in the Tampa Bay organization if he goes unclaimed.