PARIS, November 8, 2009 (AFP) - Top two seeds Roger Federer and Rafael Nadal are on course for a first showdown since May in the Paris Masters which started on Sunday.

The last time their rivalry was renewed on the court was when Federer defeated Nadal in the final of the Madrid Masters in May, after the Spaniard had been exhausted by his marathon semi-final win over Novak Djokovic.

Since then their paths have not crossed.

Nadal crashed out early in the French Open, did not play at Wimbledon to rest his troublesome knees and both men fell to Juan Martin del Potro of Argentina at the US Open.

Federer played in the Davis Cup the week after Flushing Meadows but took a long break after that returning only this week where he lost his hometown title in Basel on Sunday to Djokovic.

Nadal was once more sidelined with injury after New York, this time to a abdominal stomach muscle strain, and has played just the once since then losing to Nikolay Davydenko of Russia in the final of the Shanghai Masters last month.

Federer, who has failed to make it past the quarter-finals in six attempts at the Bercy Indoors Stadium says he is at a loss to explain his lack of success at the tournament.

"The surface is fast and suits me so there is no reason why I should not be able to go far," he said.

Nadal has made it clear that his main objective for the rest of this year is to help Spain defend the Davis Cup at home to the Czech Republic and that regaining the world No.1 spot from Federer is not what matters most to him.

"I am just taking it week by week at the moment and if it happens it happens. What is more important is being properly prepared and fit to continue winning tournaments."

Federer has a straight enough road through to the last four this time, but could run into either fourth seed Andy Murray, the winner in Valencia on Sunday, or Del Potro at that stage.

Nadal faces a potential quarter-final matchup with last year's winner Jo-Wilfried Tsonga of France with Djokovic, who won his fourth title of the year in Basel, seeded to take him on in the last four.

Tsonga will lead a strong home challenge with in-form Gilles Simon and unpredictable Gael Monfils all looking to emulate their compatriot's thrilling run to last year's title.

One Frenchman whose hopes are already over is Fabrice Santoro who lost in straight sets 6-4, 6-3 on Sunday to James Blake in what was the last match of his 20-year-long career.

"I have been able to enjoy playing this great sport for as long as I possibly could, but now it's time to stand aside and let the youngsters get on with it," the 36-year-old said.

The tournament, the final one of the ATP regular season, will also be the final salvo for two-times Grand Slam champion Marat Safin of Russia who announced early in the year that this would be his last.

The final two places for the eight-man, season-ending ATP finals in London are up for grabs with Davydenko and Fernando Verdasco of Spain currently lying seventh and eighth.

With a hefty 1,000 points going to the winner, they will have to hold off Robin Soderling, Fernando Gonzalez, Tsonga, Radek Stepanek and Marin Cilic who are all still in the hunt.

Already qualified are Federer, Nadal, Djokovic, Murray, Del Potro, and Andy Roddick.