Barring any setbacks, Mathis is expected to be reinstated by Tuesday, when the Marlins open a three-game series with the Reds.
Mathis is coming back from a broken right collarbone, which he suffered on Feb. 23 in Miami's first Spring Training game.
When Mathis arrives, who will go?
The Marlins are currently carrying three catchers -- Rob Brantly, Miguel Olivo and Kyle Skipworth, who was called up when Austin Kearns went on the bereavement list.
Olivo has been backing up, and starting occasionally against left-handed pitching.
Skipworth is expected to go back to Triple-A New Orleans. But what will the team do about Olivo? He's a veteran who has the respect of his teammates, and the pitchers.
Manager Mike Redmond said the team may keep three catchers.
Olivo can catch, play first base and pinch-hit.
Greg Dobbs has been playing first base regularly.
Chris Valaika, who had surgery on a broken left wrist Friday, was a right-handed-hitting option. But he is out two to three months.
"We don't really have another first baseman," Redmond said. "Olivo could play there."
As an organization, the Marlins don't have tremendous depth at catcher.
But if they keep three catchers, they will have to figure out what to do when Austin Kearns is ready to return.
Kearns is on MLB's bereavement list due to family-related reasons. He has returned to his home in Kentucky, and he could be transferred to the Restricted List in a couple of days, because the bereavement list is for three to seven days.