LAS VEGAS — The head of the Nevada boxing commission ordered Manny Pacquiao and Floyd Mayweather Jr. to submit to urine tests yesterday as a way of trying to break the impasse that has threatened to derail their proposed March 13 mega-fight.

Pacquiao and Mayweather must submit to the tests within 48 hours or face possible fines or suspension by the Nevada Athletic commission.

"That at least starts the ball rolling," said Keith Kizer, the commission's executive director.

The two sides signaled late in the day that there could be room for a compromise after Mayweather's representatives said there was footage on HBO's "24/7" program that showed Pacquiao having blood taken 14 days before his knockout win over Ricky Hatton.

Mayweather's promoter, Richard Schaefer, said he was told that Top Rank representatives would be talking early today to Pacquiao in the Philippines to see what cutoff date he would agree to on blood testing.

Pacquiao has said he doesn't want blood tests within 30 days of the fight. Mayweather wants blood tests to be taken two days before the fight.