Peterborough eased into the second round of the Capital One Cup with a dominant victory at Colchester.
Gabriel Zakuani headed Posh in front from Gavin McCann's cross, before Jabo Ibehre smashed home to restore parity.
But the visitors ran riot in the second half, with Tyrone Barnett heading them back ahead before Tommy Rowe unleashed a powerful strike to make it 3-1.
Posh forward Lee Tomlin scored twice to add gloss to the scoreline, curling in a fine effort before drilling home.
VIEW FROM THE DRESSING ROOM
Colchester United manager Joe Dunne told BBC Essex:
"Let's not carried away because we've been beaten 5-1 at home. What I don't want is negative feelings around the place already, I had enough of them last year.
"I'm positive about how we are going about things.
"We've taken a beating, and maybe down the season, we'll get another one. But we must stay positive. The team are going to be fine."