HOUSTON -- A Friday deadline has turned into a Saturday deadline for Gary Sheffield, who was given one additional day to determine whether he can play, or whether he will join nine other Mets on the disabled list.

Sheffield, who hasn't played since July 18 with a right leg cramp, participated in an intense lower-body workout at Minute Maid Park on Friday -- his work for the day. Sheffield was not in the lineup and was not available to pinch-hit, because the Mets did not want to waste the four games this week in which he did not play -- which can be used as retroactive time on a disabled-list stint.

Yet both Sheffield and the Mets insist that he can return Saturday, which is why he is not already on the disabled list.

"It's pretty much a cramp," Sheffield said. "If I thought I pulled it, I probably would have been on the DL."

Sheffield originally pulled up lame in a game last Saturday in Atlanta, leaving in the fifth inning. And the recently punchless Mets have become even more naked without him, batting Jeff Francoeur fourth and Fernando Tatis fifth Friday evening against the Astros.

Originally scheduled to make a decision on Sheffield before the game Friday, the Mets deferred in the hope that his lower-body workout would provide more answers. And so Sheffield ran sprints and longer distances, ran laterally and pedaled a bike -- feeling fine afterward.

How Sheffield feels Saturday morning will determine whether or not he is the Mets' cleanup hitter or their newest DL assignee. Needing to clear room for Saturday's starting pitcher, Jon Niese, the Mets have incentive to make a decision before the game.

Should Sheffield feel pain, the Mets can simply swap him for Niese. But should he feel fine, they will need to ship someone else out prior to the game.

"I feel like I can play today," Sheffield said after his workout Friday. "But at the same time, we've got to make sure how I feel tomorrow after what I did today."