Carlos Alcaraz has withdrawn from the Monte Carlo Masters due to a forearm injury, the Spanish number three seed said on Tuesday, with his place in the second round going to Lorenzo Sonego.
Alcaraz, who successfully defended his Indian Wells title last month before losing to Grigor Dimitrov in the Miami Open quarter-finals, was due to face Canada's Felix Auger-Aliassime.
Alcaraz may also have an eye on his preparation ahead of the French Open, which begins on May 20.
"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," Alcaraz posted on social media.
"I was really looking forward to playing… See you next year."
Italian Sonego, who lost in the second qualifying round to Roberto Bautista Agut, has been handed a second chance as a lucky loser, and will play Auguer-Aliassime who defeated another Italian, Luca Nardi in the first round.

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