Rafael Nadal, who is seeking a record-extending 13th Roland Garros title and a record-equalling 20th Grand Slam singles crown, was handed a relatively tough path to this year's final when the draw was made on Thursday.

The Spaniard will take on Bulgaria's Egor Gerasimov in the first round and faces a potential last-eight clash with US Open runner-up Alexander Zverev, who has never made it past the quarterfinals at the claycourt Grand Slam.

Nadal then faces a possible semifinal clash against last year's runner-up and US Open winner Dominic Thiem.

Top seed Novak Djokovic of Serbia will face Swede Mikael Ymer in the first round, where Swiss 16th seed and former champion Stan Wawrinka will take on Briton Andy Murray in the hottest opener.

Djokovic, who was ejected from the US Open after he inadvertently hit a line judge in the throat with a ball after a point, has an easier route to the final than Nadal after being drawn in the same half as Russian fourth seed Daniil Medvedev.

Canadian Milos Raonic, the world number 20, pulled out, organisers said.

Serena Williams, hoping to win a record-equalling 24th Grand Slam singles title, will start her campaign against fellow American Kristie Ahn.

The sixth seed, who was drawn in the same half as top seed Simona Halep, faces a potential fourth-round clash with US Open runner-up Victoria Azarenka.

World number one and 2019 champion Ashleigh Barty has pulled out of the tournament citing the coronavirus pandemic and a troubled preparation.

With Switzerland's Belinda Bencic a last-gasp withdrawal, only six of the top 10 in the WTA rankings will start the tournament.

The tournament was rescheduled from 24-June 7 May to 27 September-11 October amid the Covid-19 pandemic.

"This year's tournament will already go down in history because of the circumstances," French federation president Bernard Giudicelli said.

"The key words of Roland Garros 2020 are resilience and responsibility."

It will be the first year with a retractable roof at Roland Garros. (Reuters)