Marcos won his first match at Roland Garros since 2012, defeating 25th seed Ivo Karlovic 7-6(5), 6-4, 6-4 in two hours and 20 minutes.
Marcos fired eight aces, won 89 per cent (32/36) of first serve points and struck 39 winners to just 20 unforced errors. He staved off two of three break points faced while converting on three of 14 of his own.
The win was Marcos' first in straight sets at a Grand Slam since the 2013 US Open, when he topped No. 17 seed Kevin Anderson in the second round. He improved his head-to-head advantage against Karlovic to 3-1, registering his second win of the year against the big-serving Croat.
Marcos improves to an even 9-9 at the French Open and will look to score his 10th match win at the tournament against Damir Dzumhur of Bosnia and Herzegovina on Wednesday. A third round clash with second seed Roger Federer remains in the cards.
