Two goals apiece from Liam Dickinson and Bilel Mohsni helped Southend beat Northampton and move top of League Two.
John Johnson put the hosts ahead following Ben Tozer's long throw before Dave Martin volleyed home an equaliser.
Saido Berahino's 18-yard shot made it 2-1 but Dickinson's penalty levelled it after he had been fouled in the area by Northampton goalkeeper Freddy Hall.
Mohsni sealed it with two headers from Ryan Hall deliveries either side of a close-range finish from Dickinson.
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Northampton Town manager Aidy Boothroyd tells BBC Radio Northampton:
"For me, I wouldn't have been able to tell which team was at the top and which was at the bottom, for long periods.
"I think the clearest thing is that they bring a player on who scores two goals for them. We didn't switch on in the latter stages of the game.
"Was it a 5-2 game in terms of performance? Absolutely not. But we never give up. We're going to need that every week."
Southend manager Paul Sturrock told BBC Essex:
"We showed some character and attitude, the whole squad. The substitutions worked, the boy Sampson looks a handful.
"(Bilel Mohsni) has come on and turned the game upside-down and Sampson came on and gave an influence to the game as well so I'm very pleased.
"I'm excited about the squad I've got, they showed it all, we can come off the bench and change games, that's something we've probably not had for a long time."