"We've got a lot of guys who have been used a lot," Mattingly said. "So it depends on how these next couple of days go as far as that start. But right now, we're scheduled for Paul to go in that start."
Clemens got the nod on Monday in Miami's 5-3 loss to the Rockies at Marlins Park. The 28-year-old right-hander gave up three runs -- all on solo homers in the second -- over five innings.
Miami promoted Clemens from Triple-A New Orleans on Sunday to replace lefty Justin Nicolino, who went back to the Zephyrs.
Should the Marlins have to dip into their system for another starter on Saturday, Nicolino would not be an option. Because he was optioned, he has to wait 10 days before being eligible to be recalled, barring someone going on the disabled list.
Nicolino, though, is lined up to start for the Zephyrs on Saturday, and he is in line for Miami's fifth-starter spot. The lefty was impressive in his first New Orleans start on Monday, beating Oklahoma City, 4-1. In seven innings, Nicolino gave up one run on four hits with no walks and three strikeouts.
Jose Urena, who has spent time this season with the Marlins, is also in New Orleans. He is a candidate to be recalled at any time, and the right-hander is an option to either start or throw in relief.
Urena, used mostly in relief for Miami earlier in the season, last started on Friday, so he is ready to pitch either as a starter or reliever for the Marlins if they needed an immediate option.
"There's always options," Mattingly said. "Our biggest issue may be more bullpen right now than it is that [Saturday] start. How do we get to that next start?"
Joe Frisaro has covered the Marlins for MLB.com since 2002. He writes a blog, called The Fish Pond. Follow him on Twitter @JoeFrisaro and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.