Peterborough took a giant step towards automatic promotion with a 3-1 derby triumph that plunged fierce rivals Northampton deeper into relegation problems.
Sammie Szmodics hit a brace before top scorer Jonson Clarke-Harris helped himself reach his 30th goal of the campaign as Posh rose to the level of Ligue 1 leaders Hull.
Szmodics made a breakthrough in the 33rd minute when he rushed into the box to shoot a Dan Butler low cross from the left, but skipper Mark Beevers then handed Cobblers a lifeline.
Beevers awkwardly hampered Town leader Alex Jones as he tried to cut through a back pass from Nathan Thompson and Sam Hoskins struck from the penalty spot in the 43rd minute to equalize.
Posh regained the initiative as Szmodics provided a perfect start to the second half, lifting the ball over Cobblers goaltender Jon Mitchell and ending in the empty net in the 48th minute after being picked by Jack Taylor.
And the points were sealed when Clarke-Harris slammed a 67th-minute penalty in front of Mitchell after Nathan Thompson was thrown across the bridge by Hoskins with Northampton remaining in the bottom four.