Tennis stars Roger Federer and Rafael Nadal could meet in the US Open singles final, but defending champion Serena Williams and her sister Venus Williams cannot.
Swiss world number one Federer and Spanish star Nadal are on opposite sides of the the US Open draw, something not assured for the first time since 2005 because Britain's Andy Murray is ranked second.
Nadal and Federer had been 1-2 in the rankings for the past four years until this month.
Serena Williams is ranked second to Russia's Dinara Safina and so may face her sister in a semi-final.
American Devin Britton, the US college champion, will be the first foe for Federer on the Flushing Meadows hardcourts for the year's final Grand Slam event which starts Monday.
Serbian Novak Djokovic and American Andy Roddick, who could meet in a quarter-final, are in Federer's half of the draw so could face him in the semi-finals, and Murray and Nadal could meet in a semi.