Gavin Strachan was full of praise for his young side after they stood up a big test against Hull City.
The opposition were a Premier League side. The weather conditions were horrendous with wind and rain howling around North Ferriby's stadium. Posh stood up to both tests and passed with flying colours.
Goals from Tom Conlon and Regan Carthey earned a 2-1 win, preserved with some excellent defending and top goalkeeping from Luke O'Reilly.
Posh will now face Premier League giants Arsenal at London Road in the next round and manager Strachan was proud of his players for their efforts.
'I am proud of the players. The weather was awful in the first period, but it got much worse in the second half and we were up against it but the lads really stood up to that challenge. I am really pleased because we played some good football, particularly in the first half.
'I say to the players regularly that everything is a test. It was a test to play at Molineux against Wolverhampton Wanderers and it was a different kind of test against Hull because of the surroundings and the conditions.
'We have another massive test against Arsenal, but we look forward to it. What the win over Hull highlighted is the strength in depth we have in the squad because players were missing.
'We had some good performances, I thought Luke O'Reilly was excellent. He made a world class save in the first half and dealt with a lot of high balls and back passes in horrible conditions. I am very proud of the players tonight,' Strachan said.