Marcos turned in a valiant effort against No. 1 Frenchman Jo-Wilfried Tsonga in the second round at Roland Garros, but was defeated 6-7(6), 3-6, 6-3, 6-2, 6-2.
Despite facing an in-form Tsonga in front of a raucous home crowd on Court Philippe-Chatrier, Marcos fought hard, grabbing the first set in a tie-break on a service winner. Tsonga was up a mini-break at 6-5, but Marcos claimed the next three points to steal the opener. Marcos would fight back after dropping serve in the first game of the second set, reeling off six of the next seven games to take a two-set lead. He closed it out with an emphatic ace on set point.
But the lead would not hold. A quick break for the Frenchman to open the third set swung momentum to his side of the court, and the sixth seed would eventually complete the comeback after three and a half hours.
"I set up good tactics for the first two sets," Marcos said in his post-match press conference. "But I couldn't play the same tactics for the whole match. That's it.
"He's a very good player on clay, so I wanted to break up the rhythm (with drop shots). I wanted to cut short the points. I didn't want to remain far behind the baseline, so it worked out for the best for the first two sets."
Marcos, who is now 13-8 in five-set Grand Slam matches in his career, turned in a strong week on the clay of Paris, having defended his second round points from a year ago and pushing the home favourite to the brink of elimination on Thursday. He fired 49 winners, including 11 aces, and converted three of nine break chances in defeat.
Marcos will next set his sights on the grass-court season, with ATP World Tour events in Stuttgart, Halle and Nottingham, as well as the Wimbledon Championships, on his schedule.