By TIM DAHLBERG, AP Boxing Writer Tim Dahlberg, Ap Boxing Writer – Wed Dec 23, 5:12 pm ET LAS VEGAS – Manny Pacquiao has always been willing to spill blood to win a fight. He's not nearly as eager to give blood to get a fight. The fate of Pacquiao's planned March 13 megafight with Floyd Mayweather Jr. hangs in the balance. Both sides traded jabs Wednesday over Mayweather's insistence that the two submit to Olympic-style drug testing amid indications that both were open to a possible compromise. With time running short, though, Pacquiao's promoter said he's not willing to negotiate much longer to make the fight. "I think it's over tomorrow and we're going to another opponent if there is no agreement," promoter Bob Arum said. "It looks to me like they want a way out of the fight. Mayweather doesn't want to take a chance of losing." A day after Mayweather's camp threatened to scuttle the fight unless the boxers were subject to ...