French Open 2015: Novak Djokovic, Rafael Nadal canter while Thanasi Kokkinakis breaks through

Paris: World number one Novak Djokovic and defending champion Rafael Nadal stayed on course for a French Open quarter-final Thursday as teenager Thanasi Kokkinakis provided a glimpse into the sport`s future.

Top seed Djokovic survived a worrying injury scare to reach the third round with a 6-1, 6-4, 6-4 win over Gilles Muller of Luxemburg.

Nadal, chasing a 10th Paris title, enjoyed a 6-4, 6-3, 6-1 breeze past Spanish compatriot Nicolas Almagro.

Djokovic`s win over 33-year-old Muller was his 24th consecutive victory this year as he took another step towards a first ever Roland Garros title and a career Grand Slam.

However, he needed a medical timeout leading 5-4 in the second set for treatment on what appeared to be a right groin strain.

It didn`t affect him too much as he quickly wrapped up the second set with a service game to love.

He eventually wrapped up the tie on Court Suzanne Lenglen after just an hour and 45 minutes, hitting an impressive 35 winners.

The 28-year-old goes on to face 19-year-old Kokkinakis who saved three match points to beat fellow Australian Bernard Tomic 3-6, 3-6, 6-3, 6-4, 8-6 to make the third round of a major for the first time.

Sixth seed Nadal will face Andrey Kuznetsov for a place in the last 16 after the Russian defeated Austria`s Jurgen Melzer 6-1, 5-7, 7-6 (7/0), 7-5.

"I am very happy. I played a great match and was very solid," said nine-time champion Nadal who has now defeated Almagro 13 times out of 14.

"There were long games, the match was not as easy as the score may suggest."

The 28-year-old Nadal now has 68 wins at the tournament and just one loss.

Out on Court Seven, Kokkinakis, making his Roland Garros debut on a wildcard, came back from 2-5 down in the decider and saved three match points to defeat 27th seed Tomic.

Kokkinakis fired 19 aces and 71 winners to line up a third round clash with Djokovic.

The young Australian is the first teenager to reach the third round in Paris since 2008.

"Novak barely misses a ball, he`s mentally tough, lightning quick on court. The list goes on," said Kokkinakis.

"He just does everything so well and so professional. I guess that`s why he`s had such great success."

Britain`s third seed Andy Murray, twice a semi-finalist in Paris, faces Portugal`s Joao Sousa defending a 5-0 career record.

US Open champion Marin Cilic reached the third round for the fourth successive year.

The ninth-seeded Croatian fired 38 winners in a 7-6 (7/3), 6-1, 6-1 win over Italian qualifier Andrea Arnaboldi.

Cilic will face Argentine 23rd seed Leonardo Mayer who beat Jerzy Janowicz of Poland 6-4, 6-4, 6-7 (1/7), 6-1 for a place in the last 16.

This year`s second round featured a record 19 men over the age of 30.

But 33-year-old German Benjamin Becker won`t be going any further after he was forced to withdraw from Friday`s scheduled third round clash with Japan`s fifth seed Kei Nishikori because of a right shoulder injury.

Nishikori will face either Lukas Rosol of the Czech Republic or Teymuraz Gabashvili of Russia for a place in the quarter-finals.

"Very sorry to hear about Benjamin being injured. I hope he recovers fast," tweeted Nishikori, who also made the fourth round in 2013.

Becker needed two gruelling five-setters to get to the third round, seeing off Ruben Bemelmans of Belgium and Spanish 32nd seed Fernando Verdasco.

On Wednesday, Britain`s Kyle Edmund also withdrew from his second round clash against Australian 29th seed Nick Kyrgios.

Qualifier Edmund was suffering a stomach injury picked up in his five-set first round win over France`s Stephane Robert.

Kyrgios goes on to face either Murray or Sousa in the third round.