Northampton kept their play-off chances alive as goals from Steve Morrison and Ian Sampson helped them beat Boston.
Eric Sabin was lining up against his ex-Boston team-mates and saw an early effort well saved by Paul Bastock.
Rob Ullathorne's header clipped the crossbar for the home side while Graeme Jones saw Luke Chambers head off the line at the other end.
But with time running out, Morrison's speculative 25-yard drive skidded in before Sampson volleyed home.
Northampton: Harper, Chambers, Willmott, Sampson, Lyttle, Ullathorne, Reeves, Trollope, Vieira, Sabin, Smith. Subs: Thompson, Low, Carruthers, Asamoah, Morison.
Boston Utd: Bastock, Beevers, Ellender, Balmer, Chapman, Lee Thompson, Bennett, Greaves, Noble, Brown, Jones. Subs: Angel, Hocking, Croudson, Douglas, Hogg.
Referee: A Marriner (W Midlands).