Becoming a father has not affected Novak Djokovic's drive and motivation.
The top-ranked Serb won his 20th Masters title in Paris last week in his first tournament since the birth of his baby boy, Stefan. Childcare duties have not lessened his desire to finish the year as the world's top-ranked player for the third time. (Also read: Boris Becker Extends Deal as Novak Djokovic Coach)
Djokovic is also trying to become the first player to win three straight ATP Finals since Ivan Lendl in 1985-87 when the action starts on Sunday in London.
"Of course certain things change, psychologically, but when you are playing for someone, someone who is your son, of course it's an extra motivation, Djokovic said.
"My wife and I had the blessing of becoming parents recently and this is the most beautiful thing you can experience. The first tournament after that happened was in Paris, and I won without dropping a set. We should be making more kids I guess."
Unbeaten in 27 matches on indoor courts, Djokovic took a big step toward finishing the year at the top by extending his lead over Roger Federer to 1,310 points in Paris.
A potential 1,500 points are on offer in London and Federer, who will also have the opportunity to earn some extra points in Switzerland's Davis Cup final against France later this month, still has an outside chance of pipping the Serb.
But the Djokovic has been playing superbly recently and has every reason to believe he will withstand Federer's late charge.
"Obviously, there are some matches I wish I played better this year," the Wimbledon champion said. "But now I'm in a good position fighting for No. 1. I won this tournament two years in a row, I believe I can do well again this year."
Djokovic said he will make some adjustments to his schedule next season to juggle his professional calendar with his new family obligations.
"Starting next year, we are going to think about it and see what's best for the baby, this is the priority number one," he said. "Of course a father wants to participate in his baby's life and hopefully I can do it."
Djokovic said he received advice from Federer on how to cope with his new life as a father while staying competitive.
"I'm still far from him, he has four kids, and it's pretty amazing to still play at such a high level," Djokovic said.
Without his family in the British capital, the 27-year-old Djokovic will have his mind totally on tennis. He has been placed in Group A at the eight-man tournament with Australian Open champion Stan Wawrinka, U.S. Open winner Marin Cilic and Tomas Berdych.
While Djokovic has a combined career record of 41-5 against his group, Federer is in Group B along with Andy Murray, Kei Nishikori and Milos Raonic - who ended the Swiss player's run in the quarterfinals at the Paris Masters.
Federer, who is hoping to clinch the year-end top spot for a record-equaling sixth time, took a break after his loss in Paris. Having been hampered by back problems that ruined his 2013 season, the 17-time Grand Slam title winner rediscovered his form this year, coming close to winning Wimbledon and claiming five titles.
"I work hard to get as fit as possible," said the 33-year-old Swiss when asked about his longevity. "And then, understanding the body, listening to it. Understanding when it is closed to be injured and when it is fine to be played for days and weeks on it. And I also try to keep the right balance to keep the mind hungry for play."
He will be opening his campaign for a seventh ATP Finals title against Raonic, one of three newcomers at the tournament with Cilic and Nishikori.
Rafael Nadal is skipping the event after undergoing appendix surgery.