Kim Clijsters prepares to return against Marion Bartoli of France during their second round match at the US Open on Thursday. Clijsters beat the 14th seed Bartoli, 5-7, 6-1, 6-2. (REUTERS)

NEW YORK (Reuters) — All eyes were on two of the most famous pairs of knees in tennis on Wednesday as Rafael Nadal and Venus Williams were back doing what they do best at the US Open – obliterating their opponents.

As the cameras zoomed in on their stricken joints, with both former world number ones struggling with tendinitis in recent months, Williams skipped into round three with a 6-4 6-2 win over fellow American Bethanie Mattek-Sands.

Less than two hours later a merciless Nadal subjected an unfortunate Richard Gasquet, who was making his own comeback following a doping ban, to a 6-2, 6-2, 6-3 first-round mauling.

The grand slam stage, however, became a poorer place on Wednesday when Marat Safin walked out of Flushing Meadows – which he likened to a “zoo” – for the last time with a final wave to his adoring fans.

Never again will spectators at the four majors catch a glimpse of the brilliance or entertaining antics of Safin after the 2000 champion bowed out in the first round following a 1-6, 6-4, 6-3, 6-4 defeat by Austrian Juergen Melzer.

On a day of farewells, 36-year-old Fabrice Santoro’s 69th and final major outing ended in defeat. His French compatriot, former world number one and 17th seed Amelie Mauresmo, was unsure if she too would return next year after she was thumped ,6-4, 6-0, by Canadian Aleksandra Wozniak in the second round.

Comeback mum Kim Clijsters completed a forgettable day for the French when she beat 14th seed Marion Bartoli, 5-7, 6-1, 6-2.

This year’s Open is turning out to be a family affair as world number one Roger Federer and Australian Lleyton Hewitt will get a chance to compare notes on how to survive the demands of the tour with young children in tow after they set up an intriguing third-round showdown.

In a break with US Open traditions, the evening session kicked off with the men’s match between five-times champion Federer and Simon Greul.

The pesky German journeyman provided Federer with a few jitters when he held two set points in the second set and a 3-0 lead in the third but in the end could not prevent the Swiss from chalking up a 6-3, 7-5, 7-5 win.