Andy Williams came off the bench to score a stoppage-time winner as Northampton beat promotion-chasing Stevenage 2-1.
Loanee Joe Powell had given the Cobblers a first-half lead but Alex Revell appeared to have earned a point for the hosts with a 79th-minute equaliser.
But Williams, a 76th-minute substitute, kept his composure in the first minute of added time to settle the League Two contest.
The visitors took the lead after pouncing on Luther James-Wildin's mistake in the 19th minute. Forward Sam Hoskins won the ball deep in the Stevenage half before finding Powell, who slotted into the net.
The Cobblers could have added a second as Hoskins found space on the edge of the area but he curled his effort just wide of the far right post.
Boro pressed for an equaliser, with James-Wildin's cross causing problems for goalkeeper David Cornell before Northampton cleared their lines.
The home side eventually got their equaliser as the impressive Ilias Chair saw his free-kick headed in at the back post by Revell.
But Williams had the final say when he nicked the ball off Michael Timlin and drove at goal before chipping past keeper Paul Farman.