Surprise is at the heart of enthralling sporting contests and predictability is the enemy of surprise, so it's always exciting to see new faces emerge.

But that can hurt when it comes at the expense of old favourites.

Last year we watched Ash Barty, Roger Federer and Serena Williams farewell tennis.

That helped make way for the rise of world number one Iga Świątek, who already has three majors on two surfaces at just 21 years of age. And on the men's side, we saw a 19-year-old Carlos Alcaraz break through for his first grand slam at the US Open and become the first teenage men's number one, while under-25 stars Holger Rune, Casper Ruud and Felix Auger-Aliassime made clear the game was in good hands.

But now it feels like we're watching the decline of another great, with Rafael Nadal getting hit by a hip injury in his exit from the Australian Open on Wednesday.

The reigning champion admirably did not retire against Mackenzie McDonald but was badly hobbled by a hip injury during his 6-4, 6-4, 7-5 loss to the world number 65 in their second-round match.

The last time Nadal exited a major before the third round was 2016, when he was ousted in the first round of the same tournament by Fernando Verdasco, then had to withdraw before the third round at his beloved French Open with a wrist injury, skipped Wimbledon and lost in the fourth round of the US Open.

It remains the only year since 2004 when Nadal has failed to reach the last eight of any major.

Of course, Nadal was barely supposed to make it this far anyway.