Mateo Kovacic has undergone surgery on an Achilles injury and will miss the Fifa Club World Cup, Manchester City announced on Monday.
The Croatian midfielder, 31, played 42 games for the Premier League club during the recently concluded season, scoring seven goals.
"Mateo will spend the summer rehabilitating from the operation and everyone at the club wishes him a speedy recovery," City said in a statement.
Fellow midfielder Rodri, who won the Ballon d'Or in 2024, made his return to action on 20 May after eight months out with a knee injury.
But City manager Pep Guardiola has warned he will have to be managed carefully.
Guardiola's team endured a disappointing 2024/25 campaign, finishing third in the Premier League and failing to win a trophy for the first time in eight years.
They will travel to the expanded 32-team Club World Cup in the United States as defending champions after winning the competition under its previous guise in Saudi Arabia two years ago.
The month-long tournament starts on 14 June, with City opening their campaign against Moroccan club Wydad Casablanca in Philadelphia four days later.