Andy Murray survived a test of his credentials to see off South Africa's Kevin Anderson in three sets and secure a place in the semi-finals of the Valencia Open.

The world number 10, chasing his second title in the Spanish city, had endured few problems in earlier wins over Jurgen Melzer and Fabio Fognini but found seventh-seed Anderson a different prospect.

Murray lost the opening set on a tie-break, but fought back bravely to claim a 6-7 (3/7) 6-4 6-4 victory which kept the players on court for two hours and 43 minutes.

The slog may yet take its toll on third-seed Murray, but his progression to the semi-finals at least bodes well for his hopes of qualifying for next month's ATP Tour Finals for the seventh year in a row.

The pair exchanged breaks early in the match before Anderson gained the upper hand in game seven with a winning cross-court forehand.

The advantage did not last long, though, as a double fault saw the Scot break right back, with a tie-break eventually needed to decide the opening set.

And it was Anderson who seized the initiative, moving 6-3 ahead and then wrapping things up with a simple lob at the net.

Playing in his fifth successive tournament, tiredness appeared to be creeping up on Murray, who at times looked heavy in his legs and reluctant to move around the court.

The pair traded breaks once more midway through the second set but it was Murray who then gave himself a chance to edge ahead with three break points in game nine.

This time the third seed did not pass up the opportunity and produced a winner down the line to take a 5-4 lead, before serving out the set to usher in a decider.

That break seemed to be the energy-booster Murray needed, and he broke again at the start of the third set with a delightful lob which Anderson was unable to return.

The South African dug deep to get back on level terms but to no avail, and it was eventually left to Murray to serve out the match.

Unsurprisingly he did it the hard way, wasting three match points, but finally came good on the fourth thanks to Anderson's exhausted-looking forehand into the net.