"Just have to keep our fingers crossed on Jose," Tigers manager Jim Leyland said afterward. "I think it's all right."
Valverde entered the final frame with the Tigers ahead by four and, after getting two quick outs, allowed a single and double to Paul Konerko and A.J. Pierzynski, respectively.
With Alex Rios at the plate, Valverde threw a fastball to get the count to 3-1 before stepping off the back of the mound as Leyland and trainer Kevin Rand came on the field.
Right-hander Octavio Dotel replaced Valverde and walked Rios before allowing a two-run double to Alexei Ramirez. Dayan Viciedo, representing the winning run, flew out to the right-field warning track to end the game.
"For me, I'm just ready any time," Dotel said. "I wasn't surprised. When I saw [Valverde] bending down, I just tried to get ready quick."