Darren Ferguson admitted Peterborough are showing relegation form as their promotion hopes suffered another blow with a 2-1 loss at home to Coventry.
Goals from Amadou Bakayoko and Bright Enobakhare either side of half-time made it three wins in four for the Sky Blues, who leapfrogged their opponents into seventh place.
A deflected long-range strike from Louis Reed eight minutes into stoppage time proved to be a consolation goal.
Ferguson said: “I’m very, very disappointed. It’s another bad result at home. I’m bitterly disappointed at the result and the manner of the defeat.
“The 10-minute period before and after half-time was the crucial period of the game. They’ve gone ahead, then we start the second half and concede so early, and from that moment we’ve let ourselves down massively.
“Although we scored late on, Coventry have come away worthy winners.
“The manner of the goals was disappointing as they were avoidable. But it’s more the manner of what happened when it went to two-nil.
“Teams that have been successful this season like Luton, they’re mentally and physically strong. That’s what they are, that’s what you need, and clearly that’s where we’re struggling.
“We’ve had two wins out of nine since I’ve come back, which for me is embarrassing. It’s five wins in 22 games which is relegation form, it’s not top-six form. That’s the reality.”
The opening goal came three minutes before half-time. Peterborough defender Ben White’s intercepted pass allowed Luke Thomas to play in Bakayoko who calmly finished from inside the area.
White and Lafferty then failed to deal with a long ball, allowing Enobakhare to cushion home a close-range shot after 49 minutes.
Coventry squandered a number of good chances before Reed’s late consolation goal for Posh.
The only negative for the visitors was seeing Thomas stretchered off after the boot of Lee Tomlin caught him in the eye.
Manager Mark Robins said: “I think he’s fine – he’s asking if he can have a day off!
“Thankfully he’s awake and not been taken to hospital just yet. He is sat up in the treatment room and he is fine.”
Robins added: “They’re a good team. I know Darren and he goes for it. He tries to go for the jugular. We rode a storm early on – if you can call it a storm.
“We dealt with it really well and then we got a foothold and played some really good football in tough conditions. So I’m delighted – there were some really good performances in that. But not only that, we looked in control of it all game.
“The energy levels just sapped a little bit at the end. They got that goal and four minutes where we should have been in control and comfortable ended up a little more fraught.”