LONDON, June 13, 2008 (AFP) - French Open champion Rafael Nadal reached the Queen's semi-finals for the first time after out-lasting Ivo Karlovic in a gruelling three-set clash on Friday.

Nadal, the top seed, who had never gone beyond the last eight at Queen's in his two previous visits to the pre-Wimbledon warm-up tournament, now faces reigning champion Andy Roddick for a place in the final.

The Spaniard was pushed all the way by the giant Karlovic before finally winning 6-7 (5/7), 7-6 (7/5), 7-6 (7/4).

Nadal couldn't break the Croat, a Queen's runner-up three years ago, during two hours and twenty minutes of attritional action, but he managed to win a point on his opponent's serve in each of the final two tie-breaks and that was enough to edge through.

"It is a very important win because I beat a specialist on this surface, a big server," Nadal said.

"I didn't have lot of chances and it was very tough match, but I was very focused all the time."

This was grasscourt tennis of the most brutal kind and should serve as ideal preparation for Nadal's bid to overthrow Roger Federer at Wimbledon.

At 6ft 10ins Karlovic is the tallest player on the tour and uses his height to devastating affect. He hammered down over 1,300 aces in 2007 and used his heavy artillery to keep Nadal on the back foot here.

Nadal constantly wrong-footed Karlovic by putting vicious top-spin on his groundstrokes, but the Croat simply responded by firing down yet more unreturnable serves.

A tie-break was inevitable and it was Karlovic who got the decisive mini-break when Nadal tamely double-faulted.

The second set was a carbon copy of the first with neither player able to find a way to break serve.

Again a tie-break was the only way to separate them, and this time it was Nadal who snatched the advantage with a perfect passing shot to earn the mini-break he needed to win the set.

The final set tie-break was tailor-made for Nadal to show his ice-cool temperament. He dug in and unleashed a powerful return which caught Karlovic off-balance and secured the winning mini-break.

Roddick advanced without having to complete his match for the second successive round as Andy Murray pulled out with a thumb injury.

"I had a scan. I haven't pulled anything. I just sprained it a bit. Obviously it's not terrible, but it's just too sore to try and play a match," said Murray.

Roddick had reached the last eight when compatriot Mardy Fish withdrew after one set.

Lleyton Hewitt's bid for a record fifth Queen's title was halted by Novak Djokovic, the Serb second seed.

Hewitt, 27, was hoping to pull clear of Roddick, John McEnroe and Boris Becker, who all own four titles at the pre-Wimbledon warm-up event, but the Australian will have to wait another year after being dismantled 6-2, 6-2.

Djokovic was able to dicate the tempo of the match by moving Hewitt out of position with some searing groundstrokes and broke twice in each set to cruise through to his first Queen's semi-final.

"I didn't expect to win so easily. I knew Hewitt was one of the toughest players to play against on this surface," Djokovic said.

"I played probably the best tennis of my life on grass. I was returning a lot of serves, being very aggressive and patient at the same time. I put him under pressure. He made some unforced errors, crucial unforced errors, in the important moments."

Djokovic will play either David Nalbandian or Richard Gasquet.