BRADENTON, Fla. -- The Pirates' opening-day payroll will fall well short of their projections for 2007.

Or maybe not.

Ownership stated last fall that general manager Dave Littlefield could spend $50 million on payroll -- "Fifty-ish" was how Littlefield described it in the offseason -- but the 25-man roster that will travel to Houston for the first game Monday will cost $36.9 million no matter the final personnel moves this weekend.

That looks like a $13 million gap, but a high-ranking team official yesterday said the disparity is closer to $4 million.

No specifics were divulged, but extra expenses that go into payroll -- as accounted by Major League Baseball -- can include buyouts from the previous year, signing bonuses and deferred payments.

In the Pirates' case for 2007, known extra expenses include Jeromy Burnitz's $700,000 buyout, Jody Gerut's $141,667 termination fee, and signing bonuses totaling $875,000 for Cuban pitchers Yoslan Herrera and Serguey Linares. They also include -- contrary to what was previously stated by the team -- a $5.5 million payment to the Oakland Athletics to complete the Jason Kendall trade of 2004.

Those expenses, put together, cost an additional $7.22 million, still leaving an unexplained gap of about $2 million. That gap could allow for performance bonuses being triggered in some contracts. Fewer than half the players on the roster have such clauses.

Littlefield, always the seller and never the buyer at the trading deadline, was asked if he might spend his leftover $4 million in an attempt to bolster the team this season.

"You want to be the buyer," Littlefield said. "The goal is to win a world championship, and we think we're going to be significantly improved. Contending teams in July usually are looking to add a piece or two, and we'll see how it plays out. We've got to prove it through three or four months. But, obviously, having some dollars available helps you when the opportunity presents itself."

The Pirates' payroll projects to rank 28th out of the majors' 30 teams, as it did last year when the team spent $43.4 million by season's end. Only the Tampa Bay Devil Rays and Florida Marlins are sure to be lower.