Unlike in his first match, when his game stuttered and he allowed Roddick to take the second set, the British No1 raced to the finish line.
He broke Simon twice in succession to sweep into a 5-1 lead. While the Frenchman held his nerve to recover from 15-30 down to hold serve in the next game, it little but delay the inevitable as Murray took match-point with a forehand winner.
Roddick, meanwhile, revealed his injury occurred during practice yesterday.
"When I was doing a warm-up drill I just went over on it," he said.
"I can't really stop and start very quickly and when I go over on the outside it hurts. It would have been a tough prospect trying to beat Roger with no serve and not being able to move much."
