Robert Gsellman pitched well on Thursday, allowing only an unearned...

Robert Gsellman pitched well on Thursday, allowing only an unearned run in 5 1⁄3 innings against the Nationals in a preseason game on March 23, 2017. Credit: Getty Images / Joe Robbins

WEST PALM BEACH, Fla. — With 10 days left until Opening Day, intrigue hovers over the Mets’ pitching, leaving team officials wary of closing off any options as they work to answer some key questions.

Can Zack Wheeler be stashed in the bullpen? Will Matt Harvey be marooned in extended spring training? Can Robert Gsellman be the fifth starter?

“We’d like to let things play out so those decisions make themselves,” general manager Sandy Alderson said Thursday before the Mets lost to the Nationals, 1-0. “I think we’re getting to the point where that will happen.”

Three pitchers — Wheeler, Gsellman and Seth Lugo — have a shot to fill one remaining opening in the starting rotation. It also could become a three-man race for two openings if Harvey needs to build up arm strength in extended spring training, though Alderson downplayed those chances.

“I guess, theoretically, there could be some merit to it if he’s not where we’d like him to be by the end of spring training,” Alderson said. “But that’s theoretical. I don’t foresee that being the case.”

Instead, barring any setbacks, the Mets likely will need to fill only one rotation spot. They not only will have to pick one starter from Wheeler, Gsellman and Lugo but must decide where to use the two who don’t crack the rotation.

Wheeler has emerged as the wild card. Two years removed from Tommy John surgery, the righthander seemingly has weathered the worst of a bumpy rehab, consistently reaching 97 mph, although his command has been shaky. Still, he looks healthy enough to contribute immediately, which had been a question at the start of camp.

In the offseason, Alderson introduced the notion of using Wheeler in relief, an idea that endures despite various complications. Among them is Wheeler’s need for time between outings, allowing his arm to bounce back. But rather than using Wheeler in frequent one-inning bursts, when his availability could be in question, Alderson has raised the possibility of long relief.

“No,” he said when asked if using Wheeler in the bullpen has been taken off the table. “But you have to put bullpen in quotes. Is it a traditional bullpen role or a less traditional bullpen role?”

Debate has lingered within the organization about Wheeler’s viability as a reliever, according to people with knowledge of the Mets’ thinking. Spring training has done little to bring about consensus. It remains an open question where — and in what capacity — Wheeler will start a season in which he’ll be limited to roughly 120 innings.

Wheeler is one of several puzzle pieces to be maneuvered, joining Gsellman and Lugo among those whose Opening Day assignments could be settled in the coming days.

Lugo will pitch for the Mets on Monday, his first outing in camp since his departure for the World Baseball Classic. He remains in the mix in the fifth starter competition, but the Mets have shown more willingness to use him out of the bullpen. That gives the righty two avenues to make the Opening Day roster.

Gsellman faces a different scenario, with his path to the big leagues appearing to hinge on making the rotation. He has long been perceived as the front-runner for the last spot, and he did nothing to dispel that notion on Thursday. He allowed an unearned run in 5 1⁄3 innings, and manager Terry Collins said Gsellman’s outing “shows that he belongs here.”

Collins lumped Gsellman among those who could be considered as potential relievers. But two officials recently said the Mets have been far less inclined to explore using Gsellman as a reliever, mostly out of concern for disrupting the righty’s development as a starter.

Like everyone else, all Gsellman can do is wait, even though he’s done nothing but bolster his claim for a rotation spot.

“I have no idea about that until they tell me,” he said.

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