Spain's Rafael Nadal overcame a slow start to defeat Frenchman Gilles Simon 7-5, 6-4 and reach the quarter-finals of the Marseille Open on Thursday.

The world number two, who has not played a competitive match for four months because of a foot injury, returned to action this week in Marseille.

"I'm qualified for the quarter-finals but it was far from being easy today," said the 2005 French Open winner. "I'm still far from my very best but I'm happy to have won these two matches here."

In the day's main match, Simon led Nadal 5-2 before the top seed rallied to win five games in a row and wrap up the first set.

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"I think there was some room for me to achieve a great stunt tonight," said Simon. "But he (Nadal) lifted the level of his play and things begun to become very difficult for me."

In the second set Nadal, who was treated for blisters on his right foot, needed to break his opponent only once.