Defending champion Andy Roddick [Images] was stretched to the limit at the Stella Artois Championships on Thursday before securing a quarter-final place with a 6-2, 3-6, 6-4 victory over Slovakian Karol Beck.

Top seed Lleyton Hewitt [Images] also needed three sets to advance but Croatian fifth seed Mario Ancic and British teenager Andrew Murray went beyond breaking point in the third round of the pre-Wimbledon grasscourt event.

Ancic, a Wimbledon semi-finalist last year, was eliminated 7-5, 1-6, 6-3 by gifted French teenager Richard Gasquet.

In the most dramatic match of the day, cramp and an ankle injury conspired to deny 18-year-old Murray, ranked 357 in the world, the chance of an unexpected victory over sixth-seeded Swede Thomas Johansson. He lost 7-6, 6-7, 7-5.

Hewitt beat Max Mirnyi of Belarus 6-3, 1-6, 6-1 in the day's last game on a gloomy court one to set up an intriguing quarter-final against Croatian ace machine Ivo Karlovic who beat Czech Tomas Zib 6-2, 6-4.

Two years ago at Wimbledon Karlovic beat the then-defending champion Hewitt in the first round, one of the biggest shocks in tennis history.

Second seed Roddick, winner at Queen's in 2003 and 2004, was second best for much of his match against Beck but the world number 44 cracked when serving at 4-5 in the third set.

Beck doubled-faulted twice in succession to hand the American an unexpected match point and blazed a backhand out to lose.

"He played well, very smart and very crafty," said Roddick, the runner-up at Wimbledon last year. "I was definitely uncomfortable out there."

Roddick will play French seventh seed Sebastien Grosjean, whom he beat in each of the last two Queen's finals, in the last eight.

HENMAN THROUGH

Grosjean saved five match points in his 2-6, 6-3, 7-6 victory over James Blake of the US in another thrilling encounter. He won the decisive tiebreak 12-10.

Tenth seed Gasquet, who had never progressed beyond the first round at Queen's, took a significant pre-Wimbledon scalp to show he can translate his impressive claycourt form on to the slicker surface.

The 18-year-old's win over Ancic set up a quarter-final against fourth-seeded Czech Radek Stepanek who downed Briton Greg Rusedski [Images] 6-3, 7-6.

Murray was leading 5-4 in the third set against Johansson when he turned his left ankle and, stricken by cramp in his left thigh, he capitulated.

"I'm very disappointed," the Scot said. "I'm pretty annoyed I couldn't finish it. I was getting cramps and I couldn't really move."

Johansson, the 2002 Australian Open champion, faces British third seed Tim Henman in the last eight. Henman recovered from a slow start to beat Australian qualifier Chris Guccione 6-7, 6-2, 6-2.

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