The 28-year-old picked up the complaint during training to hand coach Carlo Ancelotti a major blow ahead of the new campaign.

"Petr will be out for around a month after scans showed a tear in his right calf," a Chelsea spokesman said.

Cech suffered a similar injury during Chelsea's Champions League clash against Inter Milan last February.

He returned to action in the latter stages of the season to help the Blues win the domestic double.

Ancelotti will field either Ross Turnbull or Henrique Hilario when Chelsea face Manchester United in the Community Shield on August 8 and West Bromwich in the Premier League opener six days later.