Valentin Vacherot became Monaco's first ATP Tour singles champion and the lowest-ranked player in history to win a Masters 1000 event by beating his cousin Arthur Rinderknech in Shanghai.
The world No204, who beat four-time Shanghai champion Novak Djokovic in the semi-finals, came from a set down for the sixth time in the tournament to win 4-6 6-3 6-3.
Frenchman Rinderknech struck 12 winners and committed just two unforced errors on his way to winning the opening set, but from 3-3 in the second set Vacherot broke his opponent in consecutive games to lead by a break in the third.
A medical time out for Rinderkinech at 3-2 only delayed the inevitable as Vacherot, whose previous career earnings were £380,000, secured his maiden tour-level title and the winner's cheque of £824,000.
"It is unreal what just happened. I have no idea what is happening right now. I am not even dreaming, it is just crazy," Vacherot said on the ATP Tour website.
"I am just so happy with my performances the past two weeks. I just want to thank everyone who has helped with my career since the beginning.
"There has to be one loser, but I think there are two winners today. One family that won and I think for the sport of tennis, the story is unreal.
"I feel when I am down, I have no choice and need to bring my A-game.
"In the first set I didn't do that and he was playing better than me. I took my first chance to break in the second set and from that the crowd got more involved and we put on more of a show in the second part of the match."
On the challenge of facing a player he was so familiar with, Vacherot added: "I was just trying to beat the guy on the other side of the net.
"(I tried) to put on the side that it is my cousin and the guy I have been training with and growing up with.
"It was very tough and he did a better job than me in the first set, coping with the pressure. But I just found a way to turn it around."
