Murray made short work of Jeremy Chardy in the opening round but Melzer proved a much harder opponent, Murray eventually recording a 7-6 (8-6) 7-5 triumph.

Murray was surprisingly broken twice in the first six games but Melzer's serve was not strong enough to make it count and, after spurning four set points, it was a tie-break that gave the Briton the lead.

The second set was much more straightforward for the two-time Wimbledon champion, although he wasted two match points before eventually serving out for victory.

Novak Djokovic had a much more routine clash as he eased past Horacio Zeballos 6-3 6-4.

Third seed Tomas Berdych is also into the last eight after beating Czech compatriot Jiri Vesely, while fellow seeds Ivo Karlovic and Jo-Wilfried Tsonga are also through.

It was not so good for seventh seed Philipp Kohlschreiber, though, as he was dumped out by Nicolas Almagro, and Fernando Verdasco also overcame seeded opposition in the form of David Goffin.

Meanwhile, Radek Stepanek created a little bit of history as he became the oldest quarter-finalist on the ATP Tour since Jimmy Connors in 1995, the 38-year-old beating Arthur De Greef 6-3 6-2.

There was a shock at the Chennai Open as top seed and two-time champion Marin Cilic suffered a surprise second-round defeat against Slovak qualifier Jozef Kovalik.

Cilic looked on course for victory after coming from a set down against the world number 117, but he wasted five break chances in the third and was duly punished as Kovalik converted his only one of the decider before serving out for the biggest win of his career.

Thursday also saw second-round wins for Dudi Sela, Daniil Medvedev and third seed Albert Ramos Vinolas - all three winning in straight sets.