PORT ST. LUCIE, Fla. -- Justin Turner may not be as firm a lock for the Mets’ Opening Day roster as it would seem.

A source acquainted with the Mets’ plans told ESPNNewYork.com that Turner might be dealt late in spring training, although forecasting that is premature given a Grapefruit League pitch has not been thrown.

The source also would not rule out Turner, who has an option remaining, starting the season at Triple-A Las Vegas -- although Turner would be an expensive minor league piece considering a player has to make 60 percent of his previous year’s salary, even if he’s not on the major league club.

Why trade Turner?

It’s far from a given, but there are a couple of potential reasons why it could happen:

If the Mets want to get Brandon Hicks and Omar Quintanilla on the roster as infielders, that seemingly precludes Turner making the Opening Day roster, too.

Perhaps more importantly, the Mets may have a dire 40-man roster crunch at the end of spring training if Pedro Feliciano, Scott Atchison and LaTroy Hawkins all demonstrate their worthiness to be included in the bullpen. That’s not a given, but it may be the most plausible scenario. All three are in camp on minor league deals.

In that scenario, the Mets might need to clear four spots in total on a 40-man roster that is currently full. The fourth spot might be needed for a right fielder: Marlon Byrd, Andrew Brown or Jamie Hoffmann.

If Turner were dealt for a minor leaguer, Zach Lutz -- already on the 40 and with one option year remaining -- could slip onto the roster as that corner infielder and alleviate the need to open a 40 spot.

Regardless, the Mets are going to have a big challenge late this spring training in making 40-man roster room. Reese Havens, a 2008 first-round draft choice, is the lone obvious casualty.

A team insider predicted right-hander Jeremy Hefner was too valuable to risk placing on waivers. So Hefner appears in no danger of losing his 40-man roster spot, whether or not he makes the Opening Day roster. (Hefner has an option remaining.)

How else might the Mets reduce the need for 40-man roster spots?

If Byrd were to flop in spring training, Lutz could be considered an outfielder and alleviate one spot needing to be freed.

And if Feliciano does not resemble 2010 and fails to make the club, the Mets could consider carrying one lefty, Josh Edgin, in the bullpen. Instead, a righty reliever already on the 40 -- either Greg Burke or Jeurys Familia -- could find his way onto the roster.

Meanwhile, when all is said and done, Turner still may very well be on the Mets' Opening Day roster, especially since Terry Collins is a big admirer.