TENNIS: Lleyton Hewitt's shock defeat in the fourth round here yesterday opened up a clear but testing path for two of the world's other leading young talents, Andy Roddick and David Nalbandian, who was beaten by Hewitt in last year's Wimbledon final.

Roddick reached the last eight after trailing by two sets against the Russian Mikhail Youzhny, and Nalbandian knocked out the mercurial Roger Federer, who is fast taking the Tim Henman mantle of a talented choker.

Hewitt, the world number one, succumbed to the overwhelming pressure of trying to become the first Australian to win the title since Mark Edmondson in 1976, losing 6-7, 7-6, 7-6, 6-4 against Younes El Aynaoui, who is 10 years older than the 21-year-old Hewitt, but who leaped around the Rod Laver Arena like a spring lamb as he clinched his place in the last eight with a spellbinding display of power serving in a match lasting three-and-a-half hours.

El Aynaoui hit 33 aces and managed to get almost three out four first serves in. The home crowd appeared every bit as on edge as Hewitt, who is acknowledged as one of the best returners of serve in the game, but who failed to break the Moroccan's serve once.

"He just served huge and I could not get any rhythm," said a deflated and disappointed Hewitt, who, after seven attempts - the first when he was only 15 - has yet to get beyond the last 16 of the Australian Open.

A pall of smoke, the residue of the bush fires raging around Canberra, hung over the city for much of the day and temperatures became so elevated and uncomfortable that play was called off on the outside courts for a couple of hours. It seemed likely that the retractable roof would be closed, but as Hewitt and El Aynaoui stepped onto the court in mid-afternoon the stifling heat began to relent.

The expectations surrounding Hewitt have been immense and he finally admitted it had affected him.

"Whenever you are the number one seed there is always pressure, but maybe when I'm playing in London or America I don't feel it quite as much," he said.

His small consolation was that his Belgian girlfriend, Kim Clijsters, reached the last eight on the same court a little later.

Hewitt, despite his success on the world stage, has struggled to find his way into the affections of an Australian public who appear wary of his aggressive, self-motivational behaviour on court, even though he has toned it down considerably over the past 12 months.

Hewitt had played El Aynaoui four times before and beaten him on three occasions.

"Normally he makes a few unforced errors and hits a few double faults, but today he was just in the zone," said Hewitt.

Hewitt has no huge weapons and relies on his electric speed and never-say-die attitude to impose his will. But he is vulnerable to the big guns and on this occasion the Moroccan's serve and mighty forehand boomed down an impenetrable barrage of winners, 75 in all.

This was only the third time in 26 grand slams that the Moroccan, who is based in Barcelona, had reached the last eight, the two previous occasions being here three years ago and in last year's US Open, when he lost in four sets to Hewitt. "I don't think Lleyton played his best today. I saw I had a chance and I took the opportunity," he said.

Roddick appeared to have blown his chances against 20-year-old Youzhny, but for the first time in his fledgling career he came back from two sets down. He will play El Aynaoui, for the first time, in the quarter-finals.

In a game of stark fluctuations, Nalbandian defeated Federer 6-4, 3-6, 6-1, 1-6, 6-3, and now plays the German journeyman Rainer Schuttler, who defeated James Blake of the US 6-3, 6-4, 1-6, 6-3.