Marcos will kick off his North American hard-court season at the Citi Open in Washington, D.C. after falling in the semi-finals of the Hall of Fame Tennis Championships.
Marcos suffered a tight 7-6(3), 7-6(6) defeat to second seed and two-time Newport finalist Ivo Karlovic. Despite turning aside all eight break points faced, he fell after one hour and 48 minutes.
Neither player broke serve during the encounter, which was decided by the smallest of margins. Karlovic earned an early mini-break in the first set tie-break and would later claim the decisive mini-break at 6-6 in the second. He converted on his second match point.
Marcos will now shift from the grass to the hard courts of Washington, D.C., where he is the 15th seed. Following a first round bye, he opens against either American Denis Kudla or Australian John Millman. A third round clash with top seed and home favourite John Isner looms large. No. 3 Bernard Tomic, No. 5 Steve Johnson and No. 6 Jack Sock are other threats in his half of the draw.
Marcos owns an 8-3 record in Washington, having advanced to at least the quarter-finals in each of his three appearances. He finished runner-up to David Nalbandian in 2010.