Nadal declares clean bill of health at US Open

 WORLD number three Rafael Nadal gave himself a clean bill of health after booking his place in the US Open last eight.

ALL SMILES: Rafael Nadal progressed to the US Open last eight for third time in his career

With second seed Andy Murray losing to Marin Cilic, Nadal will be eagerly eyeing a place in a first final at Flushing Meadow - the only Grand Slam missing from his resume.

Despite his recent knee and abdominal problems, Nadal looked strong as he brushed aside France's Gael Monfils at the Arthur Ashe Stadium.

He lost the first set on a tie-break but rebounded to win 6-7, 6-3, 6-1, 6-3, setting up a quarter-final with Chile's Fernando Gonzalez.

"My knees feel very good," said Nadal.

"After missing so many weeks, I'm very happy now after the last two matches I played.

"I'm here just to play my best and try to enjoy my comeback.

"For me to come back here and play in the quarter-finals is very big, a big result for me, so I'm very happy."

Gonzalez also came from behind to beat France's Jo-Wilfried Tsonga 3-6, 6-3, 7-6, 6-4 while Juan Martin Del Potro proved simply too strong for Juan Carlos Ferrero - the symmetry of his 6-3, 6-3, 6-3 win as perfect as his performance, with a 22 ace haul providing the foundation.

Meanwhile, Serena Williams hailed the comeback of Kim Clijsters ahead of their eagerly-awaited semi-final.

Williams beat Italian Flavia Pennetta 6-4, 6-3 while former world number one Clijsters - in her first Slam in two years following the birth of her daughter - brushed aside China's Li Na, having beaten Serena's sister Venus earlier in the tournament.

"Kim is such a great person and I only wish the best for her," said Serena, following her fifth consecutive straight sets win.

"It will be a great match. She has nothing to lose and is having so much fun.

"Initially I was surprised about how well she was playing but I knew she was someone to look out for."