PORT ST. LUCIE, Fla. -- The starting pitching depth the Mets sought during the offseason and believed they achieved has taken a hit. Right-handed pitcher Tim Redding, one of the four hurlers competing for the fifth spot in the rotation, has been shut down because of weakness and aching in his throwing shoulder.

General manager Omar Minaya provided no specific prognosis on Saturday morning when he announced the club's latest physical malady, but he said Redding probably won't have sufficient time to prepare to be a viable pitcher -- starter or reliever -- by Opening Day, April 6.

Redding's absence leaves veterans Livan Hernandez and Freddy Garcia and rookie Jonathon Niese as the primary candidates for the starting job, and the acquisition on Saturday of right-handed pitcher Fernando Nieve -- the Mets claimed him off waivers from the Astros -- blurs the competition for the three still-vacant slots in the seven-man bullpen. Minaya mentioned Nelson Figueroa as a possible candidate for the rotation and the long-man role, and, after mentioning Bobby Parnell, acknowledged the rookie was not likely to serve in any role other than short relief.

"That's where the organizational thinking is right now," the general manager said.

With left-handed reliever Tom Martin injured and assigned to the Minor League complex and with Redding no longer in the Opening Day mix for either assignment, the bullpen now will include some combination of three from among Parnell, Nieve, Darren O'Day, Brian Stokes and a left-handed pitcher, veteran Ron Villone and Casey Fossum being the most likely. A person familiar with the club's current evaluations said Saturday that a bullpen with one left-handed pitcher, Pedro Feliciano, still is possible. And that Stokes' status -- he has no options remaining -- enhances the chances of him being in the bullpen.

The club's regard for Parnell, higher since he made his big league debut and five other appearances in September, increased again on Friday after his work against the Tigers. If he is on the big league roster, his role almost certainly will be situational -- when a strikeout is needed.

Redding, while competing for the starting assignment, had appeared to be the pitcher most likely to fill the long-reliever role. But his altered circumstance has changed that as well.

Minaya reiterated the club's stance that the fifth starter already is in camp, his way of indicating the Mets have no designs on pursuing free agent Pedro Martinez. Minaya said there have been no negotiations with Martinez's representative, but he declined to say whether he had been in contact with the pitcher or the agent. An online report on Saturday suggested the Mets had a long-standing interest in Martinez, a notion seemingly contradicted by the club's lack of pursuit of the veteran pitcher who has said publicly he is interested in re-signing with the Mets.

Redding said his problem "comes and goes" after he emerged from the weight room Saturday morning.

Though Minaya characterized the problem as weakness, Redding acknowledged he experienced "achiness" in the back of his shoulder and that he had awakened with that sensation on Thursday.

"It's not a burn, it's not a shooting pain," Redding said.

And Redding said the discomfort is different from the general stiffness and weakness he experienced early in camp and different from "dead arm," a phenomenon pitchers typically develop late in Spring Training and occasionally in the regular season.

"There's nothing structurally wrong that we're able to distinguish," Redding said.

Redding had fared poorly in his two exhibition-game appearances, one against the University of Michigan and the second on Thursday night against the Marlins. He has allowed 14 runs and five home runs in 2 1/3 innings.

After his appearance Thursday, Redding said he hadn't felt nearly as strong as he had after throwing a bullpen session two days earlier. He said Wednesday that he had been pleased by the session and felt he had made progress in locating his pitches.

"It bugs me to know that I felt fantastic Tuesday throwing a bullpen [session] like it was July, and then two days later, I'm symptomatic," Redding said.

Redding alerted the trainers on Thursday night after he had allowed eight hits and nine runs in two innings.

"I wanted to get my throwing in, get to my pitch count," Redding said. He noted that when tried to increase his velocity, "There was nothing there."

Redding has been examined by the Mets' doctors here, but he has been examined via MRI. Minaya indicated no plans for additional examination exist and that Redding will begin programs designed to strengthen the shoulder.

Redding's condition is the third and, seemingly, the most serious malady to strike the Mets' rotation in the month since camp opened. Johan Santana experienced stiffness in his pitching elbow early in camp. But that problem passed quickly despite a degree of hysteria. Santana made his first exhibition-game appearance on Thursday, and he is schedule to pitch again Tuesday. He is on line to start the Mets' Opening Day game in Cincinnati on April 6.

Mike Pelfrey suffered a muscle strain in his lower left leg last weekend and missed a schedule start as a consequence. But he since has thrown a normal bullpen session, and he started against the Nationals on Saturday afternoon in a game the Mets lost, 6-2. He pitched four innings, putting his pitch count at 64.

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Nieve, 26, produced an 0-1 record and a 8.44 ERA in 11 relief appearances (10 2/3 innings) with the Astros last season. He pitched in 40 games -- 11 starts -- with Houston in 2006 and missed all of the '07 season after undergoing right elbow surgery. ... Pelfrey pitched for the first time since March 4. He had missed a turn of the rotation because of a strained muscle in his lower left leg. He was delighted with the effect of his curveball -- he has scrapped the slider altogether -- and a changeup he threw 11 times, once to a left-handed hitter.

"I felt [the muscle strain] a little," Pelfrey said. "Obviously, I was able to get through. It wasn't anything alarming. It's kind of the same. Today was the first day I've really tested it going all out, and it was still a little sore. Nothing I'd be worried about."

Pelfrey, Hernandez (two innings), Carlos Muniz (one) and Connor Robertson shut down the Nationals for two hits for eight innings. Brandon Knight committed an error and allowed five hits and five runs in the Nationals' decisive six-run ninth on Saturday.