The team said the right-handed Soriano broke the finger while working on fly ball drills.
Marquis had suggested he fits best as a starter -- with the Cubs or any other team -- and threatened to play elsewhere, prompting a bit of a tirade from Piniella.
"Well, if that's the case, he can go somewhere else. How's that?" Piniella said.
Piniella backed down on Sunday, saying there was no problem between the two.
"The whole thing here basically was I wasn't expecting it," Piniella said. "It sort of surprised me. But I should have handled it better, and I apologize."
Marquis is battling to keep his starting spot in the rotation after going 12-6 with a 4.60 ERA last year. The Cubs kept him on their playoff roster but had no plans to use him in the National League Division Series after a poor September.