MELBOURNE: Coming off the best season of his career, new dad Novak Djokovic joked that he needs to make some more babies.

"Ever since I became a father everything is going uphill on the tennis court," Djokovic said after winning his first-round match at the Australian Open on Monday.

Djokovic and his wife Jelena had a baby boy, Stefan, in October 2014. The No. 1-ranked player went on to have an outstanding 2015, winning three Grand Slams, 10 titles and finishing the season at No. 1 for the fourth time in five years.

"I undoubtedly had the best season and best year of my life in 2015," a clearly amused Djokovic told on-court interviewer Jim Courier before directing a message to his wife.

"Darling, I guess we got to make more babies. What can I say?" Djokovic said smiling, as the crowd erupted in laughter.

"I'm probably going to get criticized for what I said now, but anyway, going back to tennis, it's been a remarkable season," added Djokovic, a five-time Australian Open winner. "Hopefully, I can have another great start here in Australian Open and take it from here."