Novak Djokovic has shown signs that he is starting to ‘lose his level’ of tennis, according to former player Alex Corretja.

The Serbian, 37, was knocked out of Indian Wells earlier than expected and is not in top form heading into the Miami Open. Corretja suggested that his age might finally be catching up to the 24-time Grand Slam winner.

“It did happen to me, of course,” the Spaniard told TNT Sports. “You feel like you’re practising quite well and your level is quite high, and you’re playing with players and you feel like you can beat them, but somehow, when you play matches, tournaments, you struggle.

“The good thing for Novak is he’s been 100 million times better than me, and he will have more resources in these situations. But it is the same for everyone: somehow, you lose a bit of speed on your movement, you don’t hit the ball as hard, or maybe you get a bit late to the ball, or maybe things are not as clear in your head and then you start losing those matches where before, maybe you found a way.

“Once it happens, people start thinking they can beat you, and they go on court thinking ‘I’m going to hang in there because he’s struggling a little bit’, whereas before, maybe they would have given up because they knew that it was just impossible. So it’s a combination.

“It’s a bit worrying when that happens, but I’m not so sure he’s feeling that way yet. If he felt that way, it is a symptom that maybe he’s losing a bit of his level of tennis.”