Marcos fought valiantly for two hours and 56 minutes, but was eventually ousted by 18-year-old Borna Coric in the second round of the Dubai Duty Free Tennis Championships on Wednesday.
Marcos rallied from a set down to force a decider and served for the match at 5-4. The battle would progress to a third set tie-break, where at 4-all he succumbed to cramps and retired, falling 6-4, 3-6, 6-6.
In total, Marcos fired five aces and won six of 12 break point chances over the near-three hour affair. It was his first encounter against a teenager on the ATP World Tour since beating American Ryan Harrison in Brisbane three years ago.
Marcos will next travel to Indian Wells, U.S.A. for the BNP Paribas Open - the first ATP World Tour Masters 1000 event of the year. Main draw action begins 12 March.
