James Willstrop overcame a tiring John White 8-11 11-5 10-11 11-1 11-2 to win the ISS Canary Wharf Squash Classic.
Willstrop ground down White in five games at Canary Wharf
The English third seed rallied after losing the first game and gradually took control as White faded in his fourth straight marathon encounter.
Willstrop saluted the Scot afterwards and admitted: "I know the time he has spent on court this week helped me."
White, 33, said: "In the next couple of years, James will be world number one and winning all the big titles."
White admitted he was so exhausted he deliberately dropped the tempo of his performance in the fourth game in an effort to feel refreshed by the start of the decider.
He said: "I felt fine in the third at 10-7, but the next six or seven rallies just took everything out of me.
"After all the games I've had it only takes three or four hard rallied on the trot to leave me drained.
"So I threw the fourth to see how much I had left for the fifth, but he was getting everything back and at times he was just hitting the ball back to me.
"I was still trying things in the fourth and fifth but it was just squirting out or hitting the tin."