Tranmere's run of defeats against Peterborough continued with a 3-0 defeat at London Road pushing them into the League One relegation zone.
Rovers conceded early on from the penalty spot, but were denied an equaliser by the woodwork straight after half-time.
The home side added their second midway through the second-half and the third late on to seal their victory.
Tranmere face a crucial match this Saturday when they meet fellow strugglers Crewe at Prenton Park, and manager Ronnie Moore says the defence has to improve.
In his post-match interview, Ronnie said: “You can't defend the way we did, especially for the second goal.
"The third goal was unbelievable, it was reckless defending.”
Moore also felt his side paid the price for not taking their chances.
Rovers had three opportunities in quick succession at the start of the second-half but couldn't take any of them: "I'm shocked at the three goals,” said Ronnie.
“They got a penalty after five minutes which put us on the back foot but in the second-half we came out and played with a bit of freedom and enjoyment.
“We had three great chances and when you're playing a top side as these are you have to take them.
"We hit the post and it came straight out and into the keeper's hands, Ash had a header which went past the back post and Kirby has been in and the keeper made a save. While that's all happening you've got to stay in the game.”
It’s the third time this season Rovers have lost to Peterborough, who have scored 13 goals against the Wirral team.
"In the two 5-0s we were poor, but 3-0 flatters them I think.
"While it was 1-0 and even 2-0 we still had chances and if you don't take them you get punished."
Meanwhile, Moore said Liam Ridehalgh had to be substituted with a groin injury at half time.
He added: "He has tweaked his groin which could be a big loss for us because it could be two or three weeks.
"But we'll let it settle down and wait and see."
Moore made one change to the team that drew against Walsall as Jake Kirby replaced Andy Robinson on the wing. With Danny Holmes injured, Callum Morris was named among the substitutes.