Cahill went on the 10-day disabled list Wednesday -- retroactive to May 14 -- marking his second stint on the disabled list this season. He missed nine games in April with a lower back strain. In seven starts this year, Cahill is 3-2 with a 3.27 ERA.
Green doesn't expect to have an update on Cahill's condition until the team opens a three-game series against the Mets on Tuesday. It appears certain, though, that Cahill, who is eligible to come of the disabled list Wednesday, will miss more than 10 days.
With Cahill and Jered Weaver, who went on the disabled list Saturday, out of the rotation, the Padres will need to add a starter at some point during their series with the Mets.
Green said that a move would likely come in Thursday's series finale to keep the current rotation on five days' rest with an off-day on Monday. Jhoulys Chacin will start Tuesday and Jarred Cosart will take the mound Wednesday.
"We're still talking about what our options are coming off the off-day," Green said. "… We have some options that we're considering that we're not willing to divulge at this point in time."
Ryan Posner is a contributor for MLB.com based in San Diego. He covered the Padres on Sunday. This story was not subject to the approval of Major League Baseball or its clubs.