Lleyton Hewitt [Images] gave Australia's [Images] national day celebrations a giant lift when he beat David Nalbandian [Images] in a four-hour quarter-final battle at the Australian Open [Images] on Wednesday.

Hewitt drew on all his reserves of stamina and courage to beat the Argentine 6-3, 6-2, 1-6, 3-6, 10-8 and set up a semi-final meeting with Andy Roddick [Images] on Friday.

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Hewitt's victory kept alive Australian hopes of a local winner in the centenary of their national championship after Alicia Molik [Images] lost to Lindsay Davenport [Images] earlier in the day.

The 28-year-old world number one clung on desperately to beat Molik 6-4, 4-6, 9-7 in a nailbiting finish tinged with controversy after a line judge made an incorrect call on a crucial point.

Davenport plays Nathalie Dechy [Images] in Thursday's second women's semi-final after the Frenchwoman beat Patty Schnyder [Images] 5-7, 6-1, 7-5.

There was more drama when Russian Nikolay Davydenko [Images] was forced to retire from his match with second seed Roddick because of breathing problems on another scorching day in Melbourne [Images].

The American was leading 6-3, 7-5, 4-1 when Davydenko, who began showing signs of distress early in the second set, decided to quit. Davydenko, 23, later said he felt fine but was at a loss to explain his breathing problems.

"It looked pretty serious," Roddick, 22, said.

"When he called the trainer, I figured he had to be struggling a little bit, especially when I saw him with the inhaler."

Hewitt, 23, needed five sets to win his fourth-round match against Spanish teenager Rafael Nadal [Images] and was forced to go the distance again when Nalbandian fought back after dropping the first two sets.

"I just told myself to hang in there and it paid off once again," Hewitt said. "It's a long way from holding up that trophy yet but I'm hanging in there."

Nalbandian's game dropped right off in a prickly second set after a series of poor line calls which marred the match and some petulant behaviour by Hewitt.

The former world number one appeared to brush Nalbandian at one change of ends and had several altercations with officials including the umpire whom he called an idiot.

Nalbandian, 23, beaten by Hewitt in the 2002 Wimbledon [Images] final, had all the momentum going into the fifth set and although he got within two points of victory three times, Hewitt seized his chance when he broke in the 17th game and served out for victory.

WRONG CALL

Molik, one of the fastest improving players in the game, beat former world number one Venus Williams [Images] in the fourth round and almost upset Davenport as well.

She twice broke Davenport when she was serving for the match and should have gone up 8-7 in the final set when she hit an ace which was incorrectly called out.

The Australian, who turns 24 on Thursday, briefly lost her composure and went on to lose that game allowing Davenport, the 2000 champion, to serve out for victory in the next game.

"Happily I was able to serve it out in the end. It was a really tough match," Davenport said.

"It was just frustrating, when you have the match on your racket. I had a match point, she hit a great shot. Not playing the type of game that you want to play, it's a little alarming."

Molik said she was annoyed that her ace was called out but refused to blame it for her loss.

"One point doesn't decide a tennis match," she said. "The bottom line is I probably had a chance out there to win today."

Dechy won a topsy-turvy encounter with Schnyder to reach the last four of a Grand Slam for the first time in almost a decade of trying.

The 19th seed saved 11 of 13 break points in a match lasting more than two and a half hours but was angry that organisers had put them on Margaret Court Arena instead of the centre court.

"That wasn't scheduled very nicely," the Frenchwoman said.

"You feel really disappointed because you just think that nobody cares too much about this match and it's still a quarter-final of a Grand Slam."

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