It is 1 a.m. in Melbourne. Novak Djokovic has just survived five hours and fifteen minutes of Grand Slam combat against Felix Auger-Aliassime, and a journalist is asking him — as journalists always do — what comes next.

For once, the man who has mastered the press conference as thoroughly as he has mastered the return of serve has almost nothing to offer. "Let's see. Let's see. I have an extra day, which is good… Future will tell.

" Three short sentences. That silence says everything. The 39-year-old Serb is still striking the ball at a level that defies logic. He moves better than many opponents who are twenty years younger, and his mental toughness remains the most formidable weapon in men's tennis.

But a body is not a mind. It cannot be coached, calmed, or tricked into recovering faster, and after the enormous physical load he has carried since the first round, the question hanging over his semi-final against Jannik Sinner is brutally simple: how much is left? History offers a complicated answer. Djokovic has reached the semi-finals or better in six of his last seven Grand Slams — a staggering record for a player his age — yet by the end of each of those tournaments, the accumulation of best-of-five-set matches has visibly worn him down.

Last year, Sinner took all six sets from him at Roland Garros and Wimbledon without needing a tiebreak. Yet at this year's Australian Open, Djokovic reversed that story in spectacular fashion, dismantling the world number one across five brutal sets.