And the Posh boss was equally mystified at being banished from the touchline in the 79th minute after being reported for dissent by the fourth official.

"Perhaps he wanted to tell his grandchildren he sent off a Ferguson," said the young manager.

"I have no idea what I did wrong. I stayed in my technical area throughout the match and perhaps the rules need clarifying.

"The referee told me the fourth official was fed up with me, but I'll be having another word with him before we leave.

"I felt we controlled much of the game and were very unlucky to lose."

City boss Gary Johnson admitted his Championship side had to improve on a poor first-half performance which saw them fall behind to George Boyd's 17th-minute shot from 10 yards.

City skipper Louis Carey equalised with a 53rd-minute header and then set up Steve Brooker to nod an 85th minute winner.

Johnson said: "We got the result in the end, but if there had been some teacups in the dressing room within reach at that time I probably would have thrown them.

"We had to get our movement going, but people have to give credit to my players because they are always capable of lifting a performance.

"Steve Brooker has come up trumps for us with a late goal for the second successive game, but the whole team improved in the second half.

"We've started with two wins and now have an enormous game against Derby County to look forward to at the weekend."

A crowd of 5,684 did their best to generate a cup-tie atmosphere in pouring rain, but it was Posh who rose to the occasion, demonstrating why they won promotion from League Two last season.

The black point of the night was a serious knee injury to young City player Christian Ribeiro making his debut at right-back. The youngster was stretchered off after 26 minutes and taken straight to hospital with suspected ligament damage.