Watch: Novak Djokovic imitates Marin Cilic's serve during practice at Madrid Masters

Novak Djokovic is known for being an entertainer on and off the court. Earlier in his career, he often used to imitate his fellow players, including the likes of Rafael Nadal and Maria Sharapova, much to the delight of tennis fans. At the ongoing Madrid Masters, the World No. 1 imitated the service action of his good friend and former top-10 player Marin Cilic, amusing fans and onlookers alike.

During one of his practice sessions at the Madrid Open, Djokovic assumed Cilic's serving stance. The Serb also copied Cilic's customary bent-knee pose and shuffling before tossing the ball.

Here's a video of the same:

The 34-year-old opened his account for a fourth title at Caja Magica with a straight-sets win over Frenchman Gael Monfils in the second round on Tuesday.

In the process, Djokovic became the first player in ATP history to beat an opponent 18 times without losing once, breaking a tie with five other players including Roger Federer and Rafael Nadal. The win also confirmed a record-extending 369th week atop the ATP rankings for the 20-time Grand Slam singles champion.

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Novak Djokovic inches closer to potential semifinal showdown against Rafael Nadal or Carlos Alcaraz

Mutua Madrid Open - Day Six

Novak Djokovic was due to play old rival Andy Murray for the first time in over five years in the third round on Thursday. Unfortunately, the Scot will not take the court due to illness, handing Djokovic a walkover.

The Serb will take on compatriot Dusan Lajovic or Hubert Hurkacz in the quarterfinals. A win in the quarterfinals could pit Djokovic against either Rafael Nadal or Carlos Alcaraz for a place in the final.

Nadal (21-1) and Alcaraz (24-3) are two of the form players on tour this year. The two Spaniards opened their respective Madrid campaigns with straight-sets wins.

While Novak Djokovic has never faced Alcaraz on tour before, he has a storied rivalry with Nadal. While the Serb owns a slender 30-28 head-to-head advantage against Nadal, he trails 8-19 on clay. However, Djokovic could draw confidence from his Roland Garros semifinal victory last year against the King of Clay.