"It doesn't look like he's gonna make that start," Mattingly said. "But it feels more short-term than long."
Volquez, who went on the DL on July 7 after exiting his start in St. Louis two days earlier, threw over the break back in the Dominican Republic.
As of now, Miami's second-half rotation starts with Dan Straily -- who took a no-decision in Friday's 6-4 loss to the Dodgers -- followed by Jose Urena on Saturday. If Mattingly and the Marlins feel Volquez isn't ready to pitch, they can push another rested starter like Tom Koehler up to Sunday.
"Everybody is prepared for whatever we have to do," Mattingly said. "So Tom is sitting there next, and we'll see what happens."
Volquez sustained similar soreness in his knee earlier this season, but he pitched through it. He also tweaked his right ankle in his no-hitter on June 3 and pitched through that pain.
Mattingly speculated the two incidents could be related.
"We don't know if this is something form the past or something that may have kind of kicked up with the ankle [injury]," Mattingly said. "Any time you have some kind of injury, something else seems to be affected."
Rojas close to returning
Utility infielder Miguel Rojas is inching his way back to the Marlins, and Mattingly is targeting Miami's three-game set against the Reds that begins next Friday as a possible return date.
"We're home for what, six games? That's six more for him, and then we'll see where we're at," Mattingly said.
Rojas has been on the 60-day DL since May 9 with a right thumb fracture. In seven games on a Minor League rehab assignment, he's hitting .286 with two doubles.
Mattingly said Rojas could be called up in an emergency, but he's still "probably not as sharp baseball-wise as we would like him to be."
"If something would happen or we were in need of that shortstop, then Miggy is ready to go," Mattingly said.
Patrick Pinak is a reporter for MLB.com based in Miami.