Valverde said he underwent an MRI on Tuesday, and the results came back fine. The Tigers have listed him as day to day, but Valverde doesn't believe it'll be any more than a couple days.
"I don't want to be out for two months [with an aggravation]," Valverde said. "I'll take a couple days and be ready for Pittsburgh [this weekend]."
Valverde said the back wasn't bothering him while he was warming up in the bullpen on Tuesday. The first time he felt tightness and soreness was the second pitch he threw to the White Sox Adam Dunn. He pitched to three more batters after that before he winced on a 2-1 pitch to Alex Rios, prompting catcher Alex Avila to signal for head athletic trainer Kevin Rand.
In the meantime, manager Jim Leyland said setup man Joaquin Benoit will "probably be" the closer. The exception would be if Benoit has thrown a couple more days or the matchups beg for somebody else, such as left-hander Phil Coke.
The Tigers don't expect to lose Valverde long enough to put him on the disabled list. For now, however, they decided to go with an extra reliever, recalling right-hander Brayan Villarreal from Triple-A Toledo. Infielder Danny Worth was optioned to Toledo to make room.
"That's a move we didn't want to make, but it's obviously attributed to the Valverde situation," Leyland said. "We don't know when he's going to be ready to pitch, and obviously we can't pitch short down there, as you saw tonight. Danny Worth is just the victim of a situation. It's too bad, but we've got to get another arm up here."