Boston general manager Theo Epstein said he’s still talking with Mike Lowell, above, and his agents.

Journal / Bob Breidenbach

BOSTON — The Red Sox’ window of exclusivity with Mike Lowell closed at midnight last night, but that doesn’t preclude the team from continuing to negotiate with the free-agent third baseman — or change their level of interest.

General manager Theo Epstein confirmed last night that he spoke with Sam and Seth Levinson — the agents for Lowell — and that communication is expected to continue. The Sox have made Lowell a three-year offer, thought to be in the neighborhood of $40 million.

Lowell’s multi-year deal, worth $9 million annually, expired at the end of this season.

Effective at midnight last night, Lowell may now negotiate with other interested teams. Previously, teams could only express their interest without making a specific offer.

The gamble the Sox are taking is that another team may be willing to guarantee a four-year deal for Lowell, which the Sox seem unwilling to do. The Sox are wary that Lowell, who will turn 34 in February, will be in decline by the 2011 season, when the fourth year would begin.

In that way, these negotiations are reminiscent of the team’s dealings with center fielder Johnny Damon. The Sox offered Damon a three-year deal after 2005, only to have the offer trumped by the Yankees. History has shown the Red Sox made the right call on Damon, whose production declined last season. The Yankees, who will shift him to left field next season, have him under contract for two more seasons.

Faced with the prospect of losing their own third baseman, free agent Alex Rodriguez, the Yankees could again swoop in and sign Lowell, whom they drafted and signed in 1995. But the Yankees are reportedly leery of Lowell’s production in Yankee Stadium, which, with its spacious left field, tends to affect the power of right-handed hitters.

Other teams said to be interested in Lowell include the Philadelphia Phillies and Los Angeles Dodgers, though the latter also have a strong interest in Rodriguez.

Lowell’s situation may remain unresolved until the annual winter meetings, which begin Dec. 3 in Nashville, Tenn. Typically, situations tend to crystallize then for big-name free agents.

If Lowell were to take until the first week of December and then sign elsewhere, the Red Sox wouldn’t be at a competitive disadvantage, since there are no other free agents who could fill the position — beyond Rodriguez.

At the general manager meetings last week in Orlando, Fla., the Sox and agent Scott Boras spoke about Rodriguez, but only briefly. An executive with one major-league club said recently that he believes Boras already has a destination — and, perhaps, a deal in place — for Rodriguez. The Los Angeles Angels of Anaheim would appear to be the favorite for Rodriguez’s services.

While the Red Sox have not publicly ruled out a bid for Rodriguez — they nearly signed him after the 2003 season — a number of factors would have to take place for them to intensify their efforts. For one thing, Rodriguez would have to accept a far shorter deal than Boras’ stated goal of a 10-year contract.

Should Lowell get a four-year deal from another team, the Sox would almost certainly have to fill the void via trade. They could deal for another third baseman, such as the Dodgers’ Andy LaRoche, or obtain a first baseman (Conor Jackson and Dan Johnson) and shift Kevin Youkilis back to third, his original position.

smcadam@projo.com