Roger Federer returns to the French Open for the first time in four years to challenge Rafael Nadal and Novak Djokovic's bids for more records.

Nadal is chasing a record-extending 12th Roland Garros title, while Djokovic can become the first man in the Open era to hold all four Grand Slam titles at once for a second time.

Federer, 37, missed the 2016 event with a back injury and skipped the past two clay-court swings to preserve his body.

The event in Paris begins on Sunday.

Swiss Federer, a 20-time Grand Slam champion, reached the Madrid Open quarter-finals this month in his first clay-court tournament in three years.

"I feel good about my game. I feel good on the clay," he said.

Federer appears to have shaken off the leg injury that forced him to pull out of his Italian Open quarter-final last week, coming through a practice session on the Philippe Chatrier show court at Roland Garros on Tuesday without any strapping.

Serbia's world number one Djokovic is expected to provide the sternest challenge to Spaniard Nadal, while American Serena Williams will aim for a record-equalling 24th Grand Slam singles title in the women's singles - if she is fit.

Former world number one Andy Murray is not playing as he continues his recovery from a hip operation, leaving Johanna Konta and Kyle Edmund as Britain's leading hopes.

In-form Konta leads British charge

Konta has raced up the rankings - and earned herself a seeding in Paris - on the back of an impressive clay-court season in which she has reached the final of the Morocco Open and Italian Open.

The British number one, who will be seeded 26th, has lost in the first round in her four previous French Opens.

Konta, 28, is the only British woman with direct entry into the main draw after 22-year-old Katie Boulter pulled out with a back injury.

British number two Heather Watson and number five Katie Swan must qualify to reach the main draw.

Edmund, Britain's leading man, has suffered five successive first-round exits this season to drop to 31st in the rankings from 14th at the start of the year.

Cameron Norrie, who this week reached a career-high ranking of 41, and Dan Evans, who has qualified directly for a Grand Slam for the first time in two years, join Edmund in the main draw.

Britain's Jamie Murray has won six Grand Slam doubles titles, although he has yet to reach a French Open final, where his best results are a quarter-final in the men's doubles in 2017 and a semi-final in the mixed in 2011.

While some of the entry lists have not yet been published, other Britons to look out for are Joe Salisbury, Dom Inglot, Luke Bambridge, Ken and Neal Skupski in the doubles and Gordon Reid and Alfie Hewett in the wheelchair events.

Nadal 'finally' wins a title

Beating Nadal, the 17-time Grand Slam champion, on clay is widely considered the ultimate challenge in men's tennis and, once again, he is the favourite at Roland Garros.

The 32-year-old triumphed in Paris last year to become only the second player to win the same Grand Slam 11 times, following Margaret Court at the Australian Open between 1960 and 1973.

Despite dominating clay-court tournaments in the build-up to the French Open in previous years, Nadal had not reached a final this year until his triumph at the Italian Open on Sunday.

He did not drop a set on his way to the final, where he beat Djokovic 6-0 4-6 6-1 to claim his first title since August.

"You were asking for titles. Finally, I have a title," Nadal said after his 81st tournament win.

"For me, the most important thing is feeling myself playing well and healthy, with the energy that I need. If that happens, the experience is that I'm going to fight for titles sooner or later.

"I'm happy to reach that level in the last tournament before a Grand Slam."

Who can stop the King of Clay?

Top seed Djokovic, 32, is bidding to hold all four Grand Slam titles for the second time in his career - after following Australian great Rod Laver in becoming only the second man to achieve the feat in 2016.

The 15-time Grand Slam champion, who won in Paris in 2016, warmed up for the tournament by winning the Madrid Open and reaching the Rome final.

"Nadal, number one favourite, without a doubt, then everyone else," Djokovic said.

Djokovic also identified Austrian fourth seed Dominic Thiem and Italian 11th seed Fabio Fognini, both of whom beat Nadal on their way to winning the Barcelona Open and Monte Carlo Masters titles respectively, as possible threats.

Greece's Stefanos Tsitsipas, 20, is the rising star on the ATP Tour and, having beaten Federer in Melbourne and Nadal in Madrid, the sixth seed will be fancied to make a challenge in Paris.

Serena has been 'eating grass' but will she be fit?

Williams, 37, made her Grand Slam comeback from maternity leave at the French Open last year but, after reaching the Wimbledon and US Open finals, has struggled with a persistent knee injury.

The problem forced the 23-time Grand Slam champion to pull out of the Italian Open last Tuesday before her match against sister Venus.

Since losing to Karolina Pliskova in the Australian Open quarter-finals in January, Williams has played in only three tournaments - Indian Wells, Miami and Rome - and has withdrawn from all of them.

"I've just been on this diet - it's been awful," Williams, who has practised at Roland Garros this week, told the official tournament website.

"When you're sedentary, it becomes hard to manage your body. So you have to eat grass. That's kind of what I did. It was a nightmare.

"But it worked and paid off. I feel like I'm taking it one day at a time. I've been really putting in the hours in terms of keeping my cardio as much as I could with a knee injury, which is really impressive how I've been able to do it."

Halep looking to enjoy title defence

Romania's Simona Halep says she has "no expectations" as she prepares to defend her maiden Grand Slam title.

Halep, then the world number one, beat American Sloane Stephens in last year's final after losing in three previous Slam showpieces.

Only five women have successfully defended their titles at the French Open - Margaret Court, Chris Evert, Monica Seles, Steffi Graf and Justine Henin.

"I have no expectations because it's the first time when I have to defend a trophy at a Grand Slam," third seed Halep said.

"I just want to be relaxed, enjoy the tournament and try to win some matches. Nothing more."

Japan's world number one Naomi Osaka, who became the first woman since Williams in 2015 to win back-to-back Grand Slams with victory at the Australian Open, goes into her first major as the top seed.

The 21-year-old has never gone past the third round in Paris, but has reached at least the quarter-finals in each of her three clay-court tournaments this year.

Czech Petra Kvitova, who lost to Osaka in the Melbourne final, won her second WTA title of the year with victory on clay in Stuttgart last month, while Karolina Pliskova and Kiki Bertens of the Netherlands are also among the in-form players.

BBC coverage

There will be a selected radio commentary on the BBC Sport website and app, and there will also be daily live text commentaries - featuring all the best images and social media from Paris.

You can also follow BBC Tennis on Twitter and the BBC Sport Instagram account for more behind-the-scenes coverage from Roland Garros.