Scott Hairston said he remains optimistic about being available for Opening Day, although that is starting to seem like false hope, since the Mets end Grapefruit League play in 19 days.

Hairston, who is dealing with a left oblique strain, has only been getting treatment and doing cardiovascular exercises in the weight room. He hopes to start swinging a bat next week, though.

Hairston received three cortisone shots in his left side March 5, and Terry Collins has described the injury as more severe than it originally seemed.

There are several ripple effects contingent upon Hairston's fate. If he opens the season on the DL, that opens a spot for a righty-hitting backup outfielder, with Vinny Rottino the closest to fitting that profile. It also means the lefty-hitting outfielder would need to be able to back up Andres Torres in center field, with Adam Loewen and Mike Baxter the candidates. Baxter recently told Collins he was capable of playing center field, after saying to Collins upon his promotion last year he did not feel comfortable there.

Either way, the Mets also have a 40-man roster crunch. Even if Hairston is ready, they are likely to need to remove two players from the 40-man roster in order to make room for a lefty-hitting outfielder and Tim Byrdak's replacement as lefty specialist. If Hairston is unavailable and the Mets need to add Rottino or another player, that's potentially a third 40-man spot that needs to be freed up.

Finding three 40-man roster spots is going to be a challenge. Among the vulnerable players for removal seemingly would be Jeremy Hefner, Josh Satin and Armando Rodriguez. Releasing D.J. Carrasco would not clear a spot since Miguel Batista presumably would have to immediately take it.

And Jenrry Mejia and Reese Havens could not, if warranted, go on the 60-day DL (where they would not count against the 40-man roster). That's because they already have been optioned to the minors, where they will not accumulate major league service time and pay.