Marcos suffered a first-round exit in Casablanca on Wednesday at the hands of Russian qualifier Andrey Kuznetsov, 6-4, 4-6, 6-4.
Whereas Marcos was playing his first match on clay since May 2010, the up-and-coming Kuznetsov had already played four tournaments on the dirt this season before qualifying into the main draw at the Grand Prix Hassan II.
The Russian, who was junior Wimbledon champion in 2009, broke serve five times from 12 opportunities as he capitalised on a first-serve percentage of 35 per cent from Marcos and nine double faults.
On a poor day for seeds at the ATP World Tour 250 tournament, No. 4 Andrey Golubev and No. 6 Jeremy Chardy were also beaten.
Marcos will look for better fortune when he competes next week at the Monte-Carlo Rolex Masters, the third ATP World Tour Masters 1000 tournament of the season.
....... MONO ΛΙΓΟ ΚΑΙΡΟ ΞΑΠΟΣΤΑΙΝΕΙ, ΚΑΙ ΞΑΝΑ ΠΡΟΣ ΤΗ ΔΟΞΑ ΤΡΑΒΑ .......