The first set saw both players producing some top-class tennis, with not much to separate them.

Third seed Murray managed to carve out a 5-3 lead and a set point but put a forehand long which Simon managed to reach but landed awkwardly on his right ankle in doing so.

The Frenchman received an injury time-out at 3-5 40-all in which he received extensive treatment on his foot but as was to be expected could not stop Murray taking the last two points and the set.

With Simon visibly hindered in movement the stage looked set for Murray to ease through but Simon started hitting freely from the start of the second and broke the Murray serve immediately.

Unfazed, the British number one broke back to level, and with the help of some deft drop shots - much to the annoyance of the Monte Carlo crowd, surged ahead to lead 5-1.

A late push from Simon saw him break Murray and then confidently hold serve for 3-5 but Murray held his nerve to produce two match points in the next game, with a Simon forehand error on the second giving Murray the match.

Murray will now go on to face Federico Gil of Portugal in the quarter-finals who earlier defeated Gael Monfils of France 7-6 (8-6) 6-2.