Chelsea booked their fourth-round place with a resounding FA Cup win at Stamford Bridge, where John Terry was sent off.
Michy Batshuayi and Willian also found the net before Terry, back in the Chelsea side along with the fit-again Kurt Zouma, was red-carded after bringing down Lee Angol midway through the second half.
Tom Nichols pulled a goal back with 20 minutes remaining, but Pedro removed any prospect of a Peterborough comeback when he netted his second five minutes later.
Pedro’s first came when pounced after Nathaniel Chalobah’s 18th-minute shot had been parried by keeper Luke McGhee.
Batshuayi fired home two minutes before half-time after Branislav Ivanovic’s ball in from the right was cushioned into the Belgian striker’s path by Ruben Loftus-Cheek.pedro