Carlos Alcaraz has pulled out of Spain’s Davis Cup Finals squad after a hamstring issue flared up at the ATP Finals.

The world number one, fresh off a tough loss to Jannik Sinner in Turin, was told the swelling in his right hamstring made playing too risky. Spain now heads into Thursday’s quarter-final against the Czech Republic in Bologna without its biggest star.

Alcaraz, who captured the French Open and US Open this season to bring his major total to six, headed to Spain’s training camp on Monday hoping to push through. Medical tests quickly shut that idea down, revealing a strong muscle strain and heavy swelling in the back of his thigh.

He had just locked down the year-end number one ranking with three straight wins in the ATP Finals group stage, but the physical toll caught up with him. With Italy also missing Jannik Sinner and Lorenzo Musetti, Germany’s Alexander Zverev stands as the lone top 10 player at the eight-team event. Spain, meanwhile, must regroup without its 22-year-old star.