The Serbian ace is desperate for more success in what remains of his glittering career but conceded that his motivation levels have changed somewhat since the retirement of his rivals Roger Federer and Rafael Nadal.

Djokovic told Eurosport Spain: "Maybe so, but if I'm not motivated, I'm not here. I don't play anymore. I put the racquet to rest.

"I still feel the desire to play, the passion to compete is always there. I hope to push harder. The Grand Slams are tournaments where I have more motivation to do well."

The former world number one will make his latest attempt to win a 100th career title at the Madrid Open and is optimistic about being successful in his first appearance at the clay court event since 2022.

Djokovic said: "I'm always optimistic, but I don't know if I'm one of the favourites because I'm not having very good results this year.

"The level I'm looking for could come here or at Roland Garros, I hope it will be here.

"I always have very good feelings when I return to Madrid, to Spain. It's a country I love very much. I've won the Madrid Open three times in my career, with extraordinary matches against Nadal and [Carlos] Alcaraz.

"I've played little here in the last six to seven years, but I missed the Spanish public, because they know the sport well and respect tennis a lot. I have a good feeling and I hope to have a good tournament."

Djokovic could take on Alcaraz at the Madrid Open and is puzzled by the criticism that has been directed at the four-time Grand Slam winner this year.

He said: "No, I don't understand it. But the atmosphere and tradition of tennis in this country is very high. The expectation is enormous after Nadal, [Carlos] Moya, [Juan Carlos] Ferrero... they've all been world No. 1. But, listen. He's 21 years old, he's won four Grand Slams and many tournaments. What more do you want?

"You want more, but what he's done in this period is incredible."