Paris - Novak Djokovic's bid to become the first man in 43 years to hold all four Grand Slam titles at the same time hit its first hurdle on Friday when Roger Federer became a potential French Open semi-final opponent.
In stark contrast, defending champion Rafael Nadal, bidding for an historic seventh title, was left with a more comfortable passage with third seed Andy Murray, who is struggling with a back injury, as a possible semi-final rival.
World number one Djokovic, three times a semi-finalist in Paris, is the top seed at Roland Garros with Federer, the 2009 champion, seeded three and Friday's draw pitted them in the same, imposing section.
Djokovic starts against Italy's Potito Starace and could face Australia's former world number one Lleyton Hewitt, playing in Paris on a wildcard, in the second round.
Adding spice to the top half of the draw is the presence of dangerous Argentine Juan Martin del Potro, the 2009 US Open winner, who could face Federer in the fourth round.
Ninth seed Del Potro is the only player outside of the big three to have won a Grand Slam title in the last seven years.
Three years ago, the 23-year-old Del Potro took Federer to a five-set thriller in the semi-finals.
Federer starts against Germany's Tobias Kamke with big-hitting David Nalbandian a possible second round foe and Czech Tomas Berdych a potential quarter-final opponent.
Meanwhile, second seed Nadal had every reason to smile as the draw shone kindly on him.
Nadal, who equalled Bjorn Borg's record of six wins here last year, starts against Italy's Simone Bolelli and has claycourt grinders Nicolas Almagro and Juan Monaco also in his quarter of the draw.
The Spaniard could face Serbian eighth seed Janko Tipsarevic in the last eight.
Murray is Nadal's scheduled semi-final opponent, in what would be a repeat of the 2011 last four, and the Scot starts against Japan's Tatsuma Ito.