Serbia’s Filip Krajinovic celebrates defeating USA’s John Isner 6-4, 6-7 (2/7), 7-6 (7/5) in the semi-final of the ATP World Tour Masters 1000 indoor tennis tournament in Paris on Sunday. (Photo: AFP)

Paris: Serbian qualifier Filip Krajinovic stunned John Isner on Saturday with a thrilling 6-4, 6-7 (2/7), 7-6 (7/5) victory to reach the Paris Masters final and end the American’s World Tour Finals bid.

The world number 77 will take on Jack Sock in Sunday’s final, after the American beat French wildcard Julien Benneteau 7-5, 6-2 to move within one win of a Tour Finals spot.

Krajinovic, who dropped out of the world’s top 200 last year after surgery to remove an extra bone in his right wrist, dug deep to come through a deciding-set tie-break against the big-serving Isner, who struck 31 aces.

He is lowest-ranked player to reach Masters final since then-world number 191 Andrei Pavel in the French capital.

The 25-year-old reached the last four after world number one Rafael Nadal withdrew from the tournament before their quarterfinal on Friday with a right knee injury.

“I was starting to play better and better and I broke the top 100 a couple years ago and then all of a sudden they saw that I had an extra bone in my wrist,” Krajinovic said..

“It was mentally really tough because, you know, getting older and older, all sponsors, they said no to me. When I served for the match, my hand was shaking. It was tough to control the emotions, but I knew I had to stay aggressive all the way to the end. I did it, and (it’s the) best day in my life,” he added.

Isner, 32, needed to win the tournament to grab the last place for the year-ending eight-man event in London from Spaniard Pablo Carreno Busta.

Now his compatriot Sock is the only man who can deny Carreno Busta. Krajinovic saved three break points in his opening service game and grew into the contest from then on, breaking Isner in game five.