Peterborough can't win a home league game to save their lives but it's a different story in knockout competitions as Division Two rivals Grimsby discovered when edged out by the odd goal of five in an FA Cup thriller.
Delighted Posh boss Barry Fry commented: "This was a massive game for us and while we were great going forward and deserved to go through, there were times when we looked poor when we didn't have the ball." After a scrappy opening, the tie came to life with two goals in as many minutes. Posh took the lead in the 22nd minute with a right-wing break that was finished off in impeccable style by Andy Clarke.
The evergreen 35-year-old controlled Matt Gill's cross on his chest before looping the ball past goalkeeper Aidan Davison from a tight angle for his seventh goal of the campaign.
Grimsby immediately swarmed forward in search of an equaliser and did not have long to wait. Phil Jevons blasted in a free-kick that took a wicked deflection in a crowded goalmouth and trickled into the net as Mark Tyler dived in the wrong direction.
Posh regained the lead two minutes after the break with Steve Thomson grabbing his first goal for the club.
The busy ex-Crystal Palace midfielder then released Adam Newton who ran 20 yards to make it 3-1 with a superbly struck right-footed drive that flashed no more than a foot off the pitch all the way past Davison.
Grimsby made a game of it in the closing stages and after substitute Darren Mansaram headed just over the bar, Jevons ensured a grandstand finish with his second of the afternoon when substitute Marcel Cas saw a close-range header come back off a post.
But it was bitterly disappointing for Grimsby's player-manager Paul Groves who said: "We should have done better after having as many if not more of the chances.
"Now we have to buck our ideas up and start winning league games. We had tremendous support from a thousand fans at Peterborough and they must have gone home feeling as gutted as I do."