Peterborough United returned to winning ways as three goals in a six-minute spell paved the way for a convincing lunchtime derby triumph against Cambridge United.
Ephron Mason-Clark headed home Kwame Poku's cross to give them the lead and Mark Bonner's U's were still recovering from that when he tapped in his second.
Poku made it three with a deflected shot and completed his owning his own double following a Posh break in the second half before Liam Bennett headed Joel Randall's cross into his own net.
Peterborough's defeat at Wigan in their previous game ended a nine-match unbeaten run in League One, but three points against their local rivals consolidates them in fourth place in the table.
They had won their five previous EFL home matches against Cambridge, stretching back to 1997, but produced little attacking threat of note in a scrappy opening at the Weston Homes Stadium.
Mason-Clark, though, had scored one of the goals when they beat the U's 2-0 in the EFL Trophy in September and the midfielder broke the deadlock with a far post diving header in the 34th minute before Ricky Jade-Jones provided the assist for his second with a low ball into the box.
The visitors had only conceded more than twice on one occasion in the league this season, and registered clean sheets in their previous three games, but they fell further behind when Poku cut inside and his shot looped over keeper Jack Stevens.
Any hopes of a second-half fightback were snuffed out when Archie Collins won the ball just outside his own box and fed it through to Joel Randall, who picked out Poku for his second.
Cambridge strove to cut the deficit but Daniel Bilokapic saved with his legs as Fejiri Okenabirhie tried his luck from a tight angle and later kept out John-Kymani Gordon's curling effort.
But Posh had the final word through Bennett's misfortune as they scored five in a game against Cambridge for the first time since 1972.
The margin of defeat, and its impact on their goal difference, dropped Cambridge two places to 15th in the table, pending the outcome of Saturday's later kick-offs.