Roger Federer and Rafael Nadal could meet in the US Open final for the first time,and Serena and Venus Williams will not be able to reprise their sibling rivalry in the years last Grand Slam final. The top-seeded Federer and No 3 Nadal were drawn into opposite halves of the field for the US Open,which begins Monday. They have played in seven major finals as Nos 1-2,including at each of the other three Grand Slam tournaments,with Nadal holding a 5-2 edge. But because Nadal recently fell to third in the rankings,there was a possibility the two men who have dominated tennis in recent years would wind up on the same side of the bracket in New York. Instead,15-time Grand Slam champion Federer has No 4 Novak Djokovic and No 5 Andy Roddick in his half. Federer,who is seeking a sixth consecutive US Open championship,edged Roddick 16-14 in the fifth set of the Wimbledon final in July. The Williams sisters wont have a rematch of their Wimbledon final,in which Serena beat Venus for her 11th Grand Slam singles title. That was the sisters eighth final at a major,and Serena leads 6-2. But at the US Open,the second-seeded Serena and No. 3 Venus were drawn for a possible semi-final. The potential mens quarter-finals are Federer vs No 8 Nikolay Davydenko,and Roddick vs Djokovic; No 2 Andy Murray vs No 6 Juan Martin del Potro,and Nadal vs No 7 Jo-Wilfried Tsonga in the bottom half. Tough for Nadal Nadal could face Murray in the semi-finals for the second straight year at the US Open; Murray upset Nadal in 2008 to reach his first Grand Slam final. Nadals first Grand Slam action since his fourth-round loss at the French Open will start with an intriguing opponent: Richard Gasquet,the former top-10 player coming off a 2 1/2-month suspension for testing positive for cocaine. Federer starts off against American wild-card recipient Devin Britton. Federer,trying to become the first man since the 1920s to win the tournament six years in a row,could play two-time major champion Lleyton Hewitt in the third round,James Blake in the fourth,and French Open runner-up Robin Soderling in the quarter-finals. The womens quarter-finals could be No 1 Dinara Safina vs No 5 Jelena Jankovic,and No 4 Elena Dementieva vs No 6 Svetlana Kuznetsova; Serena Williams vs No 7 Vera Zvonareva,and Venus Williams vs No 8 Victoria Azarenka. Venus could wind up facing 2005 US Open champion Kim Clijsters in the fourth round. Clijsters recently came out of retirement and is returning to the tournament for the first time since winning it.