Bucharest, Romania (SportsNetwork.com) - Sixth seed Viktor Troicki was among Monday's opening-round losers at the BRD Nastase Tiriac Trophy tennis event.

Spaniard Daniel Gimeno-Traver overcame the Serbian Troicki 5-7, 6-3, 6-1 on the red clay at Arenele BNR.

Also on Day 1, rising 18-year-old Croat Borna Coric outlasted Ukrainian Sergiy Stakhovsky 6-2, 6-7 (4-7), 7-6 (7-2), Tunisian Malek Jaziri came back to best German and 2011 runner-up Florian Mayer 4-6, 6-4, 7-5 and Russian veteran Mikhail Youzhny fought back to beat Romanian wild card Marius Copil 1-6, 6-4, 6-3.

The young gun Coric saved 8-of-11 break points faced in his 2-hour, 39-minute victory over Stakhovsky.

"I am really happy with the way I played today, especially since I lost against him in Zagreb earlier this year," said Coric. "It is one of my best matches this season. I managed to stay calm even though I missed quite a few opportunities."

The top seeds in Bucharest are Frenchmen Gilles Simon and Gael Monfils, who will face Youzhny in the round of 16. Simon is a three-time champion here.

Bulgarian star Grigor Dimitrov, who is not defending his title this week, defeated Czech and then-reigning champion Lukas Rosol in last year's Bucharest final.

The 2015 champion will earn $86,400.