NOVAK DJOKOVIC fell to earth yesterday but unfortunately for the remainder of the Roland Garros field this was only a temporary slip.

The World No 1, who has lost just twice all year long, tumbled near the end of his second set against the big-serving Gilles Muller of Luxembourg on a greasy Court Suzanne Lenglen and needed extensive treatment for an injured groin.

That - plus an unusual incident where he lost concentration waiting for an errant Muller shot to fall long, only for it to skiff his racket and forfeit the point - were the only glimpses of the Serb's mortality all day long. Watched by his friend, Paris Saint Germain superstar Zlatan Ibrahimovic, he promptly picked himself up to complete a 6-1, 6-4, 6-4 win which moves him into the third round here. His opponent there is another member of the walking wounded. Thanasi Kokkinakis, the talented 19-year-old Austalian, booked his place there by battling back from two sets down against his countryman Bernard Tomic, even despite an aggravated hip.

Djokovic last night made light of his injury. "It's nothing major," said the World No 1. "It's not concern for the next match, which is the most important thing. But it wasn't pleasant. The heavier conditions made the court more wet and it was pretty slippery. I made a couple of slides that were quite, I'd say, unusual, with change of directions and I jammed the hip a little bit."

Djokovic is scheduled to meet Rafa Nadal in a quarter final par excellence, and that match-up remains on track after the No 6 seed showed signs of gathering confidence as he played his way beyond his fellow Spaniard Nicolas Almagro. Clad head-to-toe in electric blue, Nadal found himself tested but still looked lively as he disposed of the man from Murcia, a former top 10 player who is now ranked no better than 154.

Only once in their previous 13 meetings had Almagro prevailed and it didn't look likely here as soon as the Spaniard had taken a 51-minute first set. He claimed to be feeling more confident with every match, and admitted his request not to be officiated by umpire Carlos Bernardes of Brazil wasn't the first time he had made such a plea. Next up for him is Andrey Kuznetsov of Russia.

"He's a hitter, and his shots can be winners," said Nadal. "So he's very dangerous. But my objective is to keep doing what I did today. My match was a good match. I will try and continue on the same tracks. That is, to gain power. I hope I can roll out my plan."

Elsewhere in the men's competition, David Ferrer and Marin Cilic continue to look dangerous, Jeremy Chardy cleared the giant John Isner out of Andy Murray's path, while teenager Borna Coric won in five sets against Tommy Robredo. Home favourite Richard Gasquet was set to start a final set with Carlos Berlocq of Argentina when bad light intervened.

Serena Williams did things the hard way in her 5-7, 6-3, 6-3 win against Anna-Lena Friedsam of Germany, but not quite as hard as Francesca Schiavone, whose 6-7, 7-5, 10-8 win against Svetlana Kuznetsova of Russia took a gargantuan three hours 50 minutes to complete. Amazingly, this was still the best part of an hour shorter than their meeting in the Australian Open in 2011, still the longest ever female Grand Slam match.

The British contingent was cut to its customary one when Heather Watson, with heavy strapping on her shoulder, exited the competition to Sloane Stephens of the USA, 6-2, 6-4. "I've had this with my arm for a week and a bit now," she said, "but it wasn't the reason I lost." Over to you, Andy.