Add one more thing to your list of what to be thankful for this year: Negotiations for a megafight between Manny Pacquiao and Floyd Mayweather, widely considered the top two pound-for-pound boxers in the world, are officially underway. Pacquiao is coming off a 12th-round technical knockout of Miguel Cotto, a fight which sold 1.25 million pay-per-views, while Mayweather trounced Juan Manuel Marquez in a lopsided unanimous decision this past September that sold 1.05 million units. Mayweather’s victory reestablished him as a top fighter in the world after a short retirement, while Pacquiao’s earned him an unprecedented seventh title in as many weight classes, the first fighter in the history of the sport to achieve the feat. The prospective clash between the two fighters, which is being negotiated by Top Rank’s Bob Arum for Pacquiao and Golden Boy’s Richard Schaeffer for Mayweather and targeted for early 2010, would be expected to threaten most pay-per-view and revenue records.