When Rafael Nadal laboured to a first-round victory over the German qualifier Bjorn Phau here last week the common consensus was that the US Open was a tournament too far for the world No 1.
Surely not even Mr Muscles from Majorca could continue at the same pace through a summer that had seen him lose only once in four months and brought him titles at Hamburg, Roland Garros, Queen's Club, Wimbledon, Toronto and the Beijing Olympics.
Those who wrote off the Spaniard might be having second thoughts, however, after he equalled his best performance at Flushing Meadows yesterday by reaching the quarter-finals. His 6-2, 5-7, 7-6, 6-3 victory over the 20-year-old American Sam Querrey took more than three hours and was by no means convincing, but at this stage the final result is all that matters.
Querrey, who had knocked out Ivo Karlovic in a battle of the giants in the previous round, enjoyed the vociferous backing of his home crowd in Arthur Ashe Stadium and rose to the occasion on his first appearance in the fourth round of a Grand Slam tournament.
The world No 55, a man mountain at 6ft 6in and more than 14st, relies heavily on his huge serve and forehand. However, there is more to his game than brute strength, which he proved by reaching the quarter-finals on clay at Monte Carlo earlier this year. One point in the second set demonstrated his ability to surprise. A beautifully judged lob sent Nadal scurrying to the baseline before a neatly disguised and well executed drop shot delivered the coup de grâce.
Nadal, nevertheless, seemed on the way to his third successive quickfire victory when he took the first set with something to spare and made an early break in the second. From 1-2 down, however, Querrey broke the Spaniard to love in two of his next three service games. When Nadal served at 5-6 he broke him again, courtesy of huge forehands on the last two points.
The world No 1 looked sluggish under the barrage of big groundstrokes and made uncharacteristic errors on his forehand. A stiff breeze added to his difficulties and after making an early break in the third set the Spaniard dropped his serve with two double-faults at 4-3.
The rest of the set went with serve before Nadal won the tie-break 7-2, leaping into the air to celebrate when Querrey put a backhand out on his first set point. His spirits lifted, Nadal broke in the sixth game of the fourth set and served out for victory, despite a marathon seventh game in which Querrey had seven break points.
"It was very difficult, especially after my big mistake in the second set," Nadal said afterwards. "I was playing fine –nothing special but nothing bad – and had the match under control, but then he broke me. I was having trouble serving against the wind. I served very badly in the second set, but the important thing was that I played my best tennis in the tie-break."
Nadal now plays another American, Mardy Fish, who is enjoying his best US Open and spoilt Gael Monfils' 22nd birthday celebrations with a comprehensive 7-5, 6-2, 6-2 victory. The world No 35, beating a seed for the third round in succession after his wins over Paul-Henri Mathieu and James Blake, surprised Monfils by attacking the net at every opportunity.
In the late match on Sunday Novak Djokovic survived a barrage of winners from Marin Cilic, the latest boy-giant from Croatia, to win 6-7, 7-5, 6-4, 7-6.
Amélie Mauresmo's hopes of extending her recent run of improved form ended in a flurry of 14 double-faults against Italy's Flavia Pennetta. The former Wimbledon champion also made 40 unforced errors as Pennetta reached her first Grand Slam quarter-final. She now plays the form player of the summer, Dinara Safina, who beat Germany's Anna-Lena Groenefeld 7-5, 6-0.
Venus Williams continued her impressive run by beating Poland's Agnieszka Radwanska 6-1, 6-3. The 2000 and 2001 champion has dropped only 15 games in her first four matches.