By Martyn Herman
LONDON (Reuters) - Stefanos Tsitsipas confirmed his meteoric rise into the highest echelon of men's tennis by battling back to beat Austrian Dominic Thiem 6-7(6) 6-2 7-6(4) in a compelling title duel at the ATP Finals on Sunday.
The 21-year-old debutant, the youngest of the eight qualifiers for the elite season-ender at the O2 Arena, displayed resilience and flair in equal measure to become the youngest champion since Lleyton Hewitt in 2001.
Thiem edged an intense first set full of powerful baseline rallies but Tsitsipas, the first Greek player to qualify for the ATP's blue-riband event, was undaunted and responded in style.
As Thiem's level dipped, Tsitsipas surged into a 4-0 lead in the second set and then led 3-1 in the decider.
Twice French Open runner-up Thiem was not finished though and fought back to take the match into a tiebreak.
World number six Tsitsipas, the crowd favourite, led 4-1 but was pegged back to 4-4 before reeling off the last three points, sealing victory when Thiem ballooned a forehand wide.
It is the fourth successive year the tournament has had a first-time winner and incredibly it is just one year since Tsitsipas won the NextGen Finals title for the best up-and-coming players on the men's Tour.
"I have no clue how I played so well in the second set," Tsitsipas said on court. "I was nervous playing in such a big event. But I'm so relieved by the outstanding performance and the fight I showed today."
Tsistipas was the youngest player to reach the final on debut since American Jim Courier in 1991.
But he showed few signs of nerves or fatigue as he wore down Thiem with his courageous attacking game.
Thiem, who has been battling a cold all week, was hanging on at times in the first set, saving break points at 1-2 and 3-4.
But he edged the tiebreak. Tsitsipas saved one set point with an athletic volley but then offered up another chance which Thiem took by landing a powerful first serve.
Tsistipas responded to the setback by winning 16 of the first 18 points of a second set he bagged in 25 minutes.
Thiem did well to hold serve at the start of the decider but when he slapped a backhand into the net to hand Tsitsipas the first break it appeared the match was slipping away.
The Austrian, whose run to the final will see him end the year ranked fourth in the world, responded by throwing the kitchen sink at his groundstrokes, levelling the set at 3-3.
With both players refusing to take a backward step it always looked like a tiebreak would be required to separate them and so it proved.
As the crowd chanted "Tsitsipas...Tsitsipas", the Greek displayed the coolest head in the house to take the title and pocket a cheque for $2.6 million.
(Reporting by Martyn Herman; Editing by Christian Randedge and Ken Ferris)