Novak Djokovic believes that Carlos Alcaraz has already reached the level of the legendary "Big Three", the nickname given to the trio of Djokovic, Roger Federer and Rafael Nadal before the latter two's retirements.

Speaking on Thursday (April 24) ahead of his opening round match at the Madrid Open against Italy's Matteo Arnaldi, Djokovic added that Alcaraz has achieved more at his age than they had at 21 years old.

Djokovic also said that with a long career ahead of him, Alcaraz has the potential to make tennis history, and fans can expect to see the Spaniard on the grandest stages, lifting the biggest trophies for years to come.

Alcaraz earlier withdrew from the tournament, with the second seed saying he was struggling with hamstring and groin injuries ahead of his French Open title defense next month.

READ: Alcaraz withdraws from Madrid Open with injury

Alcaraz sustained the injury during the final of the Barcelona Open where he was denied a third title by Denmark's Holger Rune, who stunned the Monte Carlo Masters champion in straight sets.

Alcaraz had received a bye into the second round and was scheduled to play his first match on Friday.

He took a medical timeout during the Barcelona Open final and continued to receive treatment in the next changeover before Rune prevailed, dropping the Spaniard to number three in the world rankings.

The next major tournament in the clay-court swing is the Italian Open, a Masters 1000 event from May 7-18 in Rome, where world number one Jannik Sinner is expected to make a comeback from his doping ban.

The French Open main draw gets under way on May 25.

(Production: Stefan Haskins)