The top seed, seeking his first French Open title to complete a career grand slam, looked rusty at the start and trailed 3-0 in the opening set before he stumbled past Argentine qualifier Diego Hartfield 7-5, 7-6, 6-2 to reach the second round.

    Afterwards Federer attributed his sluggish performance to having to play Sunday rather than Monday.

    "I heard I was going to play Sunday a couple weeks ago. I was never happy about that idea. I told everybody that I didn't want to play Sunday," Federer told the post-match press conference.

    "Anyway, they decided to do it that way. That's grand slams. They don't listen to us as much as the other tournaments, which is unfortunate sometimes," he added.

    This year's French Open was brought forward a day to boost its exposure, especially on television, and reduce the risk of later disruption due to rain.

    Federer, who will play his second-round match on Wednesday, was concerned that he could lose his rhythm before his second-round match on Wednesday.

    "It's tricky because you play and then you have to stop for a few days," said the 24-year-old Swiss star.

    "I guess that if you pass the first two rounds then you feel more into the tournament." Enditem