Making a comeback on his beloved clay in Monte Carlo, Nadal suffered the semi-final loss to Fabio Fognini after one of his worst performances on clay since 2005, heading to Barcelona where Dominic Thiem ousted him 6-4, 6-4, overpowering the great rival who lost the crown at another event that he won 11 times in the past.
That said, Del Potro pushed Novak Djokovic all the way in a thrilling Italian Open quarter-final last week, and was a semi-finalist at Roland Garros past year, as well as in 2009. There is widespread agreement that the Austrian is destined to win the French Open one day.
Rafael Nadal will start his campaign for a record-extending 12th title at the French Open against a qualifier.
The defending champion was handed what looked like quite an easy draw Thursday at Roland Garros stadium, where the Spanish player attended the ceremony and said he was happy with his form.
Three-time champion Serena Williams, chasing a record-equalling 24th major, begins against Vitalia Diatchenko of Russian Federation.More news: Chrissy Teigen apologises after tweeting The Voice victory
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In the women's draw, Simona Halep will open the defense of her title against Ajla Tomljanovic.
However, either 2017 champion Jelena Ostapenko or two-time major victor and ex-world number one Victoria Azarenka await in a tricky second round for the 21-year-old Japanese star.
Nadal starts against qualifiers in the first two rounds while 37-year-old Federer, bidding to become the oldest Grand Slam title victor of all time, faces Italy's Lorenzo Sonego, ranked at 73.
Roger Federer will play his first match at Roland Garros since 2015 as he plays Italy's Lorenzo Sonego in the first round of the French Open. He reached the quarterfinals in Madrid and Rome, where he withdrew because of a right leg injury.