In a third-round match that finished after 2am local time, the sixth seed was ousted by the German 29th seed 6-4 3-6 7-6 6-7 8-6, handing Roddick his earliest exit from the event since his debut in 2002.

After the first two sets were split, both men had set points in the third. But Kohlschreiber took the tie-breaker 9-7 to move ahead.

Roddick lost his temper with umpire Emmanuel Joseph in the fourth set, but regained his composure to pinch it on the tie-break.

But though Roddick saved four match points at 4-5 in the final set, his opponent broke in the 14th game to set up a fourth-round clash with Finn Jarkko Nieminen.

Earlier, the plucky Casey Dellacqua captivated Melbourne Park, filling local hearts with pride by downing 2006 champion and serial choker Amelie Mauresmo to reach the Australian Open's last 16.

After a day session which had proved fertile for the seeds - Justine Henin, Serena Williams and Rafael Nadal won - the world No 78 provided a shock which reverberated throughout the stadium.

'It's just an absolutely wonderful feeling,' Dellacqua said sobbing, after her 3-6, 6-4, 6-4 victory as a packed Rod Laver Arena crowd, that included her grandmother, whistled and cheered.

'I am shaking so much, I am so excited.'

The 22-year-old Australian, whose father is a mechanic, provided much-needed excitement on a day when the form book ruled.

Giant-killers have been in short supply at the year's first Grand Slam, and so it continued as day five opened with champion Serena and top seed Henin slicing through to the fourth round.

They were joined by fifth seed Maria Sharapova, No 3 Jelena Jankovic, and men's No 4 Nikolay Davydenko on a bad day for the bookmakers.

Few expected Dellacqua to jam such a stick in the spokes. But she upended her French opponent with free hitting and brave counter-attacking.

Having only won one Grand Slam match before this year, she next plays Jankovic.

'I have nothing to lose, I'm just going to go for it,' she said with a grin.

Mauresmo's nerves again proved her undoing against an opponent who was bundled out in the first round in all five of her previous campaigns at Melbourne Park.

The two-time Grand Slam champion looked comfortable winning the first set but could not pull clear of Dellacqua, committing 43 unforced errors and handing her match point with a double fault, her 10th of the match.

Branded a Grand Slam choker earlier in her career, Mauresmo admitted that nerves had again played a part in her latest loss.

'Yeah, confidence and really not keeping in mind the aggression that I should have,' she said, describing herself as 'frustrated and disappointed'.

Only two seasons ago, she had Grand Slam wins at the Australian Open - after Henin pulled out mid-match with a stomach bug - and at Wimbledon.

She spent 35 weeks at No 1.

Dellacqua admitted she set out to exploit the frailties of Mauresmo.

The French player came into the tournament with a stomach muscle strain and was seeded 18 after a slide down the rankings last year, when she also suffered an appendectomy and an injured groin.

'Even in the last set when she was serving, I was love-40 down, I thought, 'Oh, she might throw in a double if I can put a little bit of pressure on her' and she eventually did - she cracked in that last game,' said Dellacqua.

Henin, the world No 1 and top seed, used her experience to grind out a 7-5, 6-4 win over Italy's Francesca Schiavone.

AGENCE FRANCE-PRESSE, REUTERS

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