Update – ESPN.com via Gazzetta dello Sport is reporting that Pirlo plans to be fit by the final group stage match against Slovakia.

Add Andrea Pirlo to the growing list of World Cup injuries.

The Italian midfielder and AC Milan star could miss an undefined number of matches after suffering a second degree calf injury in the Azzurri’s 2-1 loss to Mexico in a pre-World Cup friendly.  As they often are, the initial reports were incorrect, claiming that he could miss the entire World Cup.  The most recent reports have Pirlo missing only the friendly against Switzerland on Saturday and at least the first two matches of the group stage, as his injury usually takes 15-20 days to recover.  The Azzurri can replace him on the roster before June 14 if needed.

Pirlo’s injury comes during a busy 48 hours that saw the Ivory Coast (Drogba) and England (Ferdinand)lose stars for the entire World Cup due to injury, while the U.S. (Altidore) could have a key player out for an undefined period of time.

Andrea Pirlo’s international resume is beyond impressive.  He was named Man of the Match three times in the 2006 World Cup and was also named the third-best player in the tournament.  His corner kick led to the Italian equalizer in the final against France in 2006, and he is known for his accurate free kicks.

A long term absence for “l’architetto” could force Marcello Lippi to change his tactics for the World Cup.  During the Mexico match, he switched between a 4-2-3-1 and the 4-4-2, and the players seemed to prefer the 4-4-2.  If he stuck with a 4-4-2, possible replacements could include Sampdoria’s Angelo Palombo or Fiorentina’s Riccardo Montolivo.  However, his creativity and ability to create scoring chances may be the biggest loss if he is out beyond the group stage.