The 18th-seeded El Aynaoui earned a hard-fought, 6-7 (4-7), 7-6 (7-4), 7-6 (7-5), 6-4, victory to reach the quarter-finals in Melbourne for the second time, thus denying Hewitt a chance to become the first Australian to win the Open since Mark Edmondson in 1976.
Hewitt continued to have problems in his home country's national championship, as he failed for the seventh time in as many tries to reach the quarters.
The world's No. 1 player is just 9-7 all-time at the Australian Open. He has won a pair of Grand Slam titles, the 2001 U.S. Open and 2002 Wimbledon, but has gone only as far as the fourth round in Melbourne twice.
Younes El Aynaoui returns a shot against Lleyton Hewitt Monday at the Australian Open in Melbourne. (AP Photo/Rick Stevens)
"At the moment it's really disappointing -- there's no other way to put it -- but I didn't leave anything out there today," Hewitt said.
"I gave everything I have. When I look back on this match in a couple of weeks or a couple of months when I feel like thinking about it again, I will honestly be able to say I fought as hard as I could out there."
The key to El Aynaoui's victory was his dominant serve. Hewitt failed to convert on the only three break-point chances he had. El Aynaoui also fired off 33 aces in the match.
Hewitt's upset leaves No. 2 Andre Agassi as the highest-remaining seed in the men's draw. It also opens the door for another American, ninth-seeded Andy Roddick.
Roddick, who would have met Hewitt in the quarter-finals, made a stirring comeback from two sets down against Russia's Mikhail Youzhny in the fourth round Monday to advance in the tourney. The 20-year-old American rallied for a, 6-7 (4-7), 3-6, 7-5, 6-3, 6-2, victory for his first-ever comeback from 0-2 down.
Roddick had lost all four sets he had played in two matches against Youzhny and appeared prime for another straight-set defeat. Youzhny raced to a 4-0 lead in the first-set tiebreak and made a beautiful drop shot to win the set, then gained the only break of serve to take set two.
"Midway through the third set, I was thinking whether there was a flight out tonight," said Roddick. "I was a little frustrated, but I didn't let it get the best of me. Even when I was down, for some reason I thought I
This will be Roddick's third career quarter-final appearance in a Grand Slam event. He reached the quarters in each of the last two U.S. Opens, losing to the eventual champion each time.
In other round-of-16 action, Argentinean David Nalbandian, last year's surprise Wimbledon runner-up to Hewitt, took out No. 6 seed Roger Federer of Switzerland in five sets, 6-4, 3-6, 6-1, 1-6, 6-3.
The No. 10-sedded Nalbandian piled up eight service breaks in the match, including the lone break in the final set. He also took advantage of Federer's nine double faults and 59 unforced errors.
Nalbandian will next face Germany's Rainer Schuettler, who posted a, 6-3, 6-4, 1-6, 6-3, victory over No. 23 American James Blake to earn his first-ever Grand Slam quarter-final appearance.
Meanwhile, No. 1 women's seed Serena Williams cruised into the quarterfinals with a straight-set victory over Eleni Daniilidou of Greece in the fourth round on Monday.
Williams lost the first two games of the match, but shook off the sluggish start to complete a 6-4, 6-1 victory in an hour and seven minutes. After dropping the opening two games, Williams won six of the next eight, including a break of serve to capture the first set.
Another break gave Williams a 3-1 lead in the second set and it was all over from there, as she finished off the set in a mere 27 minutes. The 18th-seeded Daniilidou struggled throughout the match, committing nine double faults and managing only seven winners.
Williams had just 17 winners and 27 unforced errors, but her power was just too much. She blasted a forehand winner to complete the first set and another to finish the match.
Three more victories will give Williams what she has dubbed the "Serena Slam."
She has captured the last three Grand Slam events and a title in Melbourne would make her the first woman to hold all four major crowns since Steffi Graf completed a similar "Slam" with an Australian Open triumph in 1994.
Next up for Williams will be 25th-seeded American Meghann Shaughnessy, who rallied for a 5-7, 6-2, 6-4 victory over No. 20 Elena Bovina of Russia.
Bovina had plenty of chances throughout the match, but converted only two of her 12 break-point opportunities, while Shaughnessy took advantage by breaking serve on four of her eight chances.
The women's quarter-finals get underway Tuesday when Venus Williams takes on Daniela Hantuchova and Justine Henin-Hardenne squares off against Virginia Ruano Pascual.
with files from Sports Network
