The world number one successfully defended his Australian Open title last month and the Spaniard conceded that his rival is the man to beat on the court at the moment.

Alcaraz said: "Jannik is the best right now.

"He has lost only four or five matches in the past year, so it is crazy. I know people say who is better out of us. They say Jannik is better or some say me. It is all discussion.

"But for me, I think for a tennis player, we have to face Jannik and he is winning everything he is playing. He is focused every time, so I think he is the best. Every tournament he plays, he makes the final or lifts the trophy."

Alcaraz's hopes of glory in Melbourne were dashed by a quarter-final defeat to Novak Djokovic although he does not consider the tournament to be a "missed opportunity" in his quest to add to his four Grand Slam wins.

The world number three said: "I don’t feel that it was a missed opportunity against Novak.

"I really wanted to win the tournament and felt I was able to but Novak played an unbelievable match.

"Facing Novak in the quarter-finals at a Grand Slam is the worst thing. It was a pretty good match.

"I have tried to take the good things about that match and will look ahead now."

Alcaraz is back in action at the ATP 500 Rotterdam Open this week and confessed that he had been feeling unwell since returning from Australia.

He said: "I spent a few days at home after Australia, but I got a cold. I was struggling a little bit at home. I could only train for two days and then I had to rest until the cold got better.

"But spending time at home, it doesn’t matter if you are sick, it is always great, having your family there. It allows you to be fresh mentally, to travel again."