Andy Murray in Vienna last-eight, keeps alive his bid to dethrone Novak Djokovic as world No. 1

Vienna: Andy Murray defeated France`s Gilles Simon for the 16th time on Thursday to reach the Vienna ATP quarter-finals and keep alive his bid to snatch Novak Djokovic`s world number one ranking.

The Olympic and Wimbledon champion eventually triumphed 4-6, 6-2, 6-2 after two hours and 40 minutes in a match which saw Murray commit an uncharacteristic 58 unforced errors.

Simon was almost as sloppy, hitting just three fewer.

"It was a very long match, but I expected it to be very hard because it`s just that way against Gilles. You play a lot of long points. You feel like the harder you hit the ball, the harder it comes back," said Murray.

"You just have to try to use some variety, some slice and drop shots, and find that balance to get him out of his rhythm."

Murray, the 2014 champion in Vienna, goes on to face John Isner on Friday for a place in the semi-finals.

If he wins the Vienna title and Paris crown next week, Murray could unseat Djokovic as world number one as long as the Serb star loses before the final in the French capital.

After dropping the first set on a frustratingly slow court, a weary-looking Murray had to save six break points in the second game of the second set to stay in contention and two more in the fourth.

But it was all one way traffic after those blips with the world number two sweeping four games in succession to level the match.

Simon, who had won just two of his 17 matches against Murray before Thursday, required a lengthy medical timeout before the final set to treat a blister on his right foot.

Despite hanging on for 2-2, Murray repeated the punishment he dished out in the second set to take the match.

Unseeded Serb Viktor Troicki earlier defeated third seeded Dominic Thiem of Austria 6-2, 7-5 a result which qualified Gael Monfils into the eight-man field at the season-ending ATP World Tour Finals in London.

Defending champion David Ferrer, the Spanish fifth seed, also made the quarter-finals by seeing off Portugal`s Joao Sousa 6-2, 7-6 (7/4).