The Spaniard, recently overtaken as world number two by Jannik Sinner, had been due to face Felix Auger-Aliassime in the second round after receiving a first-round bye but is struggling with a forearm problem.

Alcaraz wrote on social media: “I have been working in Monte Carlo and trying to recover until the last minute from an injured pronator teres in my right arm, but it was not possible and I cannot play! I was really looking forward to playing… See you next year!”

The 20-year-old won his first title since last summer’s Wimbledon in Indian Wells last month but was then beaten by Grigor Dimitrov in the quarter-finals of the Miami Open.

It is an important part of the season for Alcaraz, who is due to defend his titles in Barcelona and Madrid over the next month. He has been replaced in the draw by Italy’s Lorenzo Sonego.

Djokovic played his first match since Indian Wells after choosing to skip Miami and then parting ways with long-time coach Goran Ivanisevic.

With former Serbian doubles specialist Nenad Zimonjic guiding him from the stands, Djokovic, now the oldest men’s singles number one in history, eased to a 6-1 6-2 victory over Russia’s Roman Safiullin.

The 36-year-old said on Sky Sports: “I’m very pleased. Even the games that I lost, I had break points in those games. Really good first match at the start of the clay season. I hope to maintain this rhythm.”

Draper took on 10th seed Hubert Hurkacz and for the second year in a row lost a very tight contest.

The British number two forced a deciding set and then broke Hurkacz, champion on clay in Estoril last week, when he served for the match at 5-4 but the Pole played a brilliant tie-break to win 6-4 3-6 7-6 (2).

Draper’s exit ends British interest in singles, with Cameron Norrie and Dan Evans also losing in the first round.