Marcos nearly survived a marathon second set tiebreak, but in the end it was World No. 4 Stan Wawrinka emerging with the title 6-4, 7-6(13) at the Dubai Duty Free Tennis Championships.
Competing in his 13th ATP World Tour final and second at the 500 level, Marcos is flying high despite the loss, following a strong week at the Aviation Club in Dubai. He will return to the Top 40 of the Emirates ATP Rankings for the first time in three years and has his sights set on cracking the Top 30 in 2016.
"I didn't win the tournament this week but I won a lot more," Marcos told the assembled media following the match. "I won my confidence back. I'm happy I'm back and playing this kind of tennis now. It's just to continue improving and play at this level throughout the year.
"The goal for this season is the Top 30. That was a goal that we put with my team. I want to put a realistic goal."
Marcos took it to the fourth-ranked Wawrinka throughout the one hour and 54 minute battle. Serving down 0/40 at 4-5 in the first set, he fought off four set points before eventually succumbing. He would drop just 10 points on serve in the second set, which would finish in a marathon tiebreak.
Marcos clawed back from two mini-breaks down at 3-0 to pull level. He refused to go down quietly, saving match points at 7-6, 11-10 and 13-12. With a chance to send the final to a decider, he held five set points but was unable to convert. Wawrinka eventually sealed the victory on the 28th point of the tiebreak. It was the longest tiebreak in an ATP World Tour final since 2004, when Andy Roddick beat Mardy Fish 7-6(13), 6-4 in San Jose.
"I think just playing this level more often was the difference," Marcos added. "I think I was in control of the match until 3-2. Then I got broken twice. Then I think I played much better in the second set. I was more in control and I found a way to get it to a tiebreak.
"In the tiebreak, I think I was a bit unlucky there. That was the difference. But with more matches throughout the year at this level would make me go in there and believe from the beginning that I can win and not wait three, four games to start believing. I can see a bit more experience from Stan playing at this level at these big tournaments."
Marcos takes home 300 ranking points and $240,340 in prize money. With wins over three seeded opponents in Dubai and a new Top 40 spot, he will look to ride the momentum as the year continues.