LONDON, Nov 7 (Reuters) - Novak Djokovic no longer hits the panic button when faced with a crisis, he just keeps calm and waits for his chance.
The five-times grand slam champion was as cool as a cucumber on Wednesday as he withstood the best that fierce rival Andy Murray could throw at him to earn his second successive victory at this year's ATP World Tour Finals.
World number one Djokovic eventually prevailed 4-6 6-3 7-5 in another energy-sapping duel with the Briton he has been locking horns with since they were 11-year-olds.
Murray got the better of Djokovic in an epic U.S. Open final in September to win his first grand slam but Djokovic has won four of their seven meetings this year, including the last two.
In the Shanghai Masters final last month Djokovic saved five match points before downing Murray and while he was never in quite as much trouble on Wednesday, he still needed those survival instincts to finally subdue the Scot after being outplayed for the first hour.
"A calm mind always wins," the 25-year-old Djokovic, who matured into one of the sport's most ferocious competitors since his more combustible early days, told reporters.
"I've learned what I need to do. I try to take from every experience the best that I can and mature every year as a player and as a person. I've had many matches that I was coming back from a set down or match points down."
Djokovic has made a habit of winning from match point down and his record in deciding sets is up there with the best.
His Australian Open final victory over Rafa Nadal this year took nearly six hours, that having spent nearly five hours beating Murray in the semis.
There was also last year's U.S. Open semi-final when he saved two match points against Roger Federer to leave the Swiss reeling.
Even in defeat against Murray at this year's Flushing Meadows final he battled back from two sets down before succumbing in five.
"Confidence plays a key role for any person on this planet," Djokovic, who will end a second successive year as world No.1 said. " "Especially for the athletes at this level.
"You need to try to rely on your strength in your game and you need to believe in your shots, believe in your instincts.
"When you have that positive mindset, when you believe in your game, you have better chances of winning those crucial points."
Djokovic will face Tomas Berdych in his final round-robin match on Friday. (Reporting by Martyn Herman, editing by Pritha Sarkar)