MELBOURNE: The secret to Novak Djokovic’s post-30 success? Not his best-in-tennis return. Or his limb-twisting, body-bending court coverage. Or even his baseline consistency or clutch gene.

No, ask Djokovic to explain how he keeps playing so well at this age, and the Australian Open’s defending champion points to a quality he says he shares with rivals Roger Federer and Rafael Nadal.

“Roger has talked about this as well, Rafa as well, that age is just a number. It’s not just a cliche, but it’s really something that I feel like the three of us have in common. It’s really the way we approach career and our everyday life,” Djokovic said during a news conference before the year’s first Grand Slam tournament begins on Monday.

“I think we found a way, a formula, to balance private [and] professional life, so we are able to kind of excel in tennis and still be able to compete at the highest level after many years, still be motivated, still be mentally fresh and, of course, physically prepared and fit to compete in best-of-five-sets with young players that are coming up.”