If the long-toss session goes well, manager Brad Ausmus said, Zimmermann will likely try to throw a bullpen session Sunday morning. How he gets through that would determine whether he has a chance to start on the trip or will need to be replaced.
Zimmermann's spot in the Tigers' rotation was originally slated to fall on Saturday's game in Oakland, but thanks to Thursday's off-day, Detroit can move up Mike Pelfrey, Justin Verlander and Anibal Sanchez to start on their regular four days' rest. By doing that, the Tigers won't need Zimmermann's spot until next Tuesday against the Angels in Anaheim, the fifth game after the off-day.
If the Tigers need a replacement, they can backdate Zimmermann's DL stint to Monday, the day after Zimmermann pitched. That timetable would have him eligible to return on June 7 against the Blue Jays, but it also means somebody would have to make at least two starts in his place.
The Tigers' replacement options could depend a lot on how Shane Greene fares in his second Minor League rehab start, this time for Triple-A Toledo on Wednesday morning. Greene has been on the 15-day DL since the end of April with a blister on his right middle finger. That has healed, and Greene is now building up the innings he lost to the DL stint.
If Greene gets through Wednesday's rehab start OK, the Tigers could bring him back to start early next week on normal or extra rest. Michael Fulmer, the top prospect called up to fill Greene's spot, could then stay in the rotation as well, delaying a decision on the two pitchers.
Though the Tigers want to be cautious with Zimmermann and not make a mild groin strain into a more severe one, they also clearly need Zimmermann's outings while they sort out the rest of their rotation. Zimmermann, who turned 30 on Monday, had delivered at least seven innings in four consecutive starts before the groin strain forced him out of Sunday's start in the sixth. He still got the win, moving to 7-2 with a 2.52 ERA in his first American League season.
Jason Beck has covered the Tigers for MLB.com since 2002. Read Beck's Blog, follow him on Twitter @beckjason and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.