World number ones Novak Djokovic and Naomi Osaka as well as three-time champion Serena Williams target the second week and places in the last 16 at Roland Garros on Saturday.

Here, AFP Sport takes a look at the challenges they face on the seventh day of the tournament:

Novak Djokovic (SRB x1) v Salvatore Caruso (ITA)

Head-to-head: First meeting

Djokovic continues his bid to become only the second man in history to hold all four Slams at the same time twice. The top seed has not lost in Paris as early as the third round since 2009 and has made at least the quarter-finals every year since.

He has been untroubled at Roland Garros this year, easing through in straight sets against Hubert Hurkacz and Swiss lucky loser Henri Laaksonen.

Caruso, ranked at 147, has won his first matches at a major in Paris having made it through qualifying.

There’s a world between Djokovic and the 26-year-old Italian with his $131 million earnings making Caruso’s $400,000 appear small change.

Naomi Osaka (JPN x1) v Katerina Siniakova (CZE)

Head-to-head: Osaka leads 1-0

Dubbed by some as the ‘battle of big hair’, Osaka hopes for a more comfortable outing against number 42 Siniakova, the world’s top-ranked doubles player who is in the last 32 in Paris for the third time.

Top seed Osaka was two points away from defeat in the first round against Anna Karolina Schmiedlova and came back from a set and break down to see off Victoria Azarenka in round two.

Siniakova, 23, has two career singles titles as well as two Grand Slam doubles crowns, including Roland Garros in 2018 alongside Barbora Krejcikova

Serena Williams (USA x10) v Sofia Kenin (USA)

Head-to-head: First meeting

Serena Williams, the three-time champion, is bidding to reach the second week in Paris for the 13th time as she continues her pursuit of equalling Margaret Court’s record of 24 Grand Slam titles.

Russian-born Kenin, 20, wasn’t even born when Williams made her debut in Paris in 1998 when she reached the last 16.

Playing in the third round at Roland Garros for the first time, the world number 35, won’t be overawed.

“She’s a machine,” said her doubles partner Andrea Petkovic.

“She has a great attitude. She gets angry at herself but then it’s ‘OK, next point, it’s all good’.

“She doesn’t miss a ball, plays great depth and it’s impossible to push her back.”