Marcos is set to make his 13th appearance at Roland Garros, where he will open against Colombia's Santiago Giraldo in the first round.
In search of his first match win on clay since 2016, Marcos is seeking a strong run of results at the second Grand Slam of the year. His best result in Paris came in 2007, when he reached the Round of 16.
This year, Marcos finds himself in the bottom half of the draw, with fourth seed Grigor Dimitrov, former champion Novak Djokovic, the electric Nick Kyrgios and home hope Gael Monfils all in his quarter.
Marcos will open against Giraldo in what will be their third head-to-head meeting. He is 2-0, with hard-court wins in Kuala Lumpur in 2010 and Miami in 2014. Victory over Giraldo would set a second-round date against either 13th seed Roberto Bautista Agut or Denis Istomin. Djokovic, who lifted the trophy in 2016, is a potential third-round opponent.
In doubles, Marcos is set to team up with Greece's Stefanos Tsitsipas. The teenager is one of the rising stars of the ATP World Tour.