Murray overcomes big-serving Croat

The 20-year-old's tactics were exemplary, making it difficult for the 6ft 10ins Croatian to employ his preferred serve-volley game as he won four of five break points.

The match was predictably short of rallies, but Murray's flair eventually enabled him to prevail to set up a last-eight meeting with either Tommy Haas or Fernando Verdasco.

Both players held their opening service games but Murray - winner of the only previous meeting in the SAP Open final in San Jose last year - then threw in a sloppy game, handing an early first break to Karlovic when he netted a forehand.

The big-serving Croat comfortably held to open up a 3-1 lead, with Murray responding in kind in a match containing predictably short rallies.

Three blistering returns helped the Scot to break back in the sixth game before the first set went to a tie-break, with Murray squandering two set points before prevailing at the third attempt.

Karlovic, who was previously stranded on the baseline by Murray's groundstrokes, was able to advance to the net in the second set and took full advantage of his favoured approach, comfortably closing out the tie-break to take the match to a deciding set.

Murray bounced back, going 3-0 up with a break in the second game and looked set to ease to victory.

But Karlovic broke back in the seventh game before Murray responded immediately.

Two phenomenal cross-court forehands earned Murray a break point which he claimed at the first attempt to earn a chance to serve out the match. And he advanced with ease, closing out the match with a delightful drop shot.