Marcos was pushed to the brink, but survived a thrilling quarterfinal encounter at the Antalya Open on Thursday.
With hot and humid conditions testing both players, Marcos defeated Indian qualifier Ramkumar Ramanathan 6-7(0), 6-3, 7-6(6) after two hours and 43 minutes. He will appear in his second ATP World Tour semifinal of the year, having also reached the final four in Auckland.
Marcos fired nine aces and claimed an impressive 85 percent of first serve points, while benefitting from 11 double faults by his opponent. Meeting for the first time, Ramanathan took the early lead after capturing the opening tiebreak 7-0, but Marcos fought back with an immediate break to open the second set. He would force a deciding set with another break in the ninth game.
The match would be decided in a third-set tiebreak, where Ramanathan fought off five straight match points from 6-1 down. But Marcos stayed determined to win, prevailing on his sixth opportunity to close out the match with a blasted return winner.
Appearing in a grass-court semifinal for the fourth consecutive season (Nottingham 2014-15, Newport 2016), Marcos will bid to reach his second ATP World Tour final on the surface. Ten years ago, he advanced to the title match at the Gerry Weber Open in Halle, Germany.
He will face Japan's Yuichi Sugita on Friday. It will be the first match on Centre Court, with play beginning at 10am local time in Antalya. Marcos has never faced the 28 year old from Tokyo.