Atlanta ? Michael Vick has taken another hit – and this one could cost him nearly $20 million.

Already facing prison time, the disgraced quarterback lost the first round in his financial battle with the Atlanta Falcons when an arbitrator ruled Tuesday that Vick should repay much of the bonus money he got while secretly bankrolling a gruesome dogfighting ring.

The case is far from over. The players’ union said it would appeal the ruling by Stephen B. Burbank, a University of Pennsylvania law professor and special master who oversaw last week’s arbitration hearing in Philadelphia.

The Falcons argued that Vick, who pleaded guilty to federal charges for his role in the long-running operation, knew he was in violation of the contract when he signed a 10-year, $130 million deal in December 2004.

The team said he used proceeds from the contract to fund his illicit activities and sought the repayment of $19,970,000 in bonuses he was paid over the last three years.

Any money the Falcons recover from Vick would be credited to its future salary cap, a huge step in recovering from the loss of the team’s franchise player. Atlanta (1-4) is off to a dismal start with Joey Harrington at quarterback.

“We are certainly pleased with today’s ruling,” the Falcons said in a statement. “It is the first step in a process that our club has undertaken in an attempt to recoup significant salary cap space that will allow us to continue to build our football team today and in future years.”

In a highly technical, nine-page ruling, Burbank said the Falcons were entitled to $3.75 million of the $7.5 million bonus that Vick was paid after signing the deal in 2004, $13.5 million of the $22.5 million in roster, reporting and playing bonuses he was paid in 2005 and 2006, and $2.72 million of the $7 million roster, reporting and playing bonus that he received this year.

Burbank took a different tact than his ruling last year in a bonus dispute involving former Denver Broncos receiver Ashley Lelie.

In that case, the arbitrator ordered the Broncos to repay $220,000 to Lelie, who reportedly had to give up about $1 million in fines, lost bonuses and a prorated portion of his signing bonus to get out of the final year of his Denver contract after a dispute over playing time.

“We have reviewed the decision handed down by Special Master Stephen Burbank and believe it is incorrect,” the NFLPA said in a statement. “We will now appeal his ruling.”

The case goes to U.S. District Court Judge David Doty in Minneapolis, who still has jurisdiction over the antitrust suit filed by players following the 1987 strike.

Giving teams more financial leeway than he did in the Lelie case, Burbank said Falcons were entitled to recover bonuses for future services that Vick won’t be able to earn because of his dogfighting admission. He was suspended indefinitely without pay by the NFL, in addition to losing millions in lucrative endorsement deals.