Alexander Zverev ended US Open champion Stan Wawrinka's 11-match winning run in finals, claiming the St Petersburg Open title with a 6-2 3-6 7-5 victory.
Son of Russian former professional Alexander Sr, 19-year-old Zverev claimed his first trophy on the ATP Tour by inflicting Wawrinka's first final defeat since he went down to Nicolas Mahut in the Rosmalen Grass Court Championships in June 2013.
The two players went into the final without having dropped a set and it was the Swiss top seed whose record was spoiled first, Zverev taking two of the three break points that came his way to snatch the lead.
Wawrinka quickly hit back, moving 3-1 up in the second set before breaking again to force a decider, in which he soon led by the same scoreline.
However, third seed Zverev drew level and a wide forehand from his opponent gifted him the chance to serve for the championship.
Wawrinka saved one championship point with a brilliant cross-court backhand, but a passing shot gave the German the title in his third career final.