Dubai, UAE  - Novak Djokovic survived a fright to join Andy Murry with a win into the quarter-finals of the Barclays Championships on Wednesday as he overcame determined Czech Jan Hernych 6-3, 3-6, 6-4.

The challenger, who won just four matches on the ATP last season, gave the top seed a battle before Djokovic pulled through.

"He put up a great fight and had nothing to lose. You can't always perform at your best but it's important to stay focussed. I was able to do that tonight," said the winner.

Confident Andy Murray used his growing body of experience to best advantage, improving his serve to win his first match over Arnaud Clement 6-2, 6-3.

The Scots second seed came good over the veteran to set up a clash with a second Frenchman Thursday in Richard Gasquet.

"I dictated the match with my serve and didn't give him many chances after my first couple of service games," said Murray. "I obviously managed to get into a lot of his service games and put a bit of pressure on him,

"Nobody plays their best every single match," said the winner of two titles in 2009. "The only important thing is that you win. Tonight, I adjusted well, and I hope I do the same tomorrow."

Murray said he is still having trouble with his injured ankle but playing with strapping is preventing further problems.

"It's still sore, it just changes where it hurts from day to day. Sometimes it's on the serve, and sometimes it's moving to my forehand.

"Sometimes it hurts more when I'm walking rather than running."

Number 3 Frenchman Gilles Simon beat Teimuraz Gabashvili of Russia 6-1, 6-2.

Spain's number 4 Ferrer ousted German Philip Kohlschreiber 6-4, 6- 2 while Croatian fifth seed Marin Cilic beat Julien Benneteau of France 6-3, 4-6, 7-5.

Russian Igor Andreev, number 6, overcame compatriot Dmitry Tursunov 5-7, 6-4, 6-3.

Israeli Andy Ram was bundled out in his opening doubles match, leaving organisers to stand down on intense, airport style security erected around the controversial Israeli.

The fourth-seeded Ram and Kevin Ullyett, losing finalists at the weekend in Marseille, were beaten by Marat Safin and David Ferrer 6- 3, 3-6, 10-8 in the first round.

A huge security presence surrounded the Ram doubles contest, with spectators required to pass thorough metal detectors and no electronics or bottles of water allowed in the sparsely populated stands.

The majority seemed to have fronted up to see the charismatic Safin.

"I enjoyed my stay in Dubai," said the 28-year-old Ram who was allowed in on a special dispensation visa by the UAE government. "Coming to the court with a couple of bodyguards was a nice experience.

"During the warmup I was just thinking tactics."

Security around the Aviation club was ramped up to levels more suitable for Barack Obama than a mere tennis player - even a Roger Federer or a Rafael Nadal.

The men's ATP tournament follows last week's drama-filled WTA event, where Israeli Shahar Peer was denied a visa by the UAE. Ram was let in as a special concession as outrage flared among Jewish and other groups around the world. (dpa)