Influential Italy midfielder Andrea Pirlo is facing a race against time to prove his fitness for Italy's World Cup defence after suffering a calf injury in Thursday's friendly defeat to Mexico.

Pirlo has been ruled out of the Azzurri's final warm-up match against Switzerland in Geneva on Saturday after picking up the injury that could rule him out for up to three weeks.

Italy team doctor Enrico Castellacci admitted the injury was a concern to the medical team but was prepared to give the 31-year-old every opportunity to feature in South Africa. He told Sky Italia: "Pirlo's injury is something that worries me but fortunately there's time."