World No. 204 Valentin Vacherot beat his cousin Arthur Rinderknech in three sets to win the Shanghai Masters on Sunday. Qualifier Vacherot, the lowest-ranked Masters 1000 finalist in history, triumphed 4-6, 6-3, 6-3.

The all-family final, pitting the 54th-ranked Rinderknech from France and 204th-ranked Vacherot from Monaco, is one of the tournament's unlikeliest endings to date. Vacherot's coach and half-brother, Benjamin Balleret, described it as a "fairytale."

The championship contest was just the third ATP Masters 1000 final in history to feature two unseeded players.

Elder cousin Rinderknech went ahead first, breaking with a backhand in the third game, following three unforced errors from Vacherot. That was enough for the 30-year-old to claim the set in an otherwise well-matched duel.

With the legendary Roger Federer watching from the stands, the second set continued in much the same vein, as neither player was able to make headway early on. Rinderknech faced a break point in the eighth game and fended it off with an ace, but failed to convert a subsequent advantage to hold.

He found himself on the brink again due to an unforced error that saw him hit the ball into the net, and the 26-year-old Vacherot did not miss his chance this time, coming through in the clutch to force a decider.

The third set went off with a bang, with Vacherot taking his cousin to break point almost immediately to snatch the first game. He looked increasingly dangerous as Rinderknech, seemingly flagging in the humidity, scrambled to save multiple break points in the third and fifth games.

France's World No. 54 received treatment on his back after the fifth, having almost been broken four times.

A partial revival followed, making for some tense rallies that energized the crowd, but Vacherot broke again in the ninth game to seal the title, doubling over in disbelief after clinching his and Monaco's first-ever title on the ATP Tour.