Steve Tilson is still searching for his first win as Lincoln manager after Northampton secured a 2-0 victory at Sincil Bank.
Dean Beckwith smashed Town ahead on 37 minutes when he reacted quickly to drill past Lincoln keeper Joe Anyon after Billy McKay's shot came back off the post.
Abdul Osman nearly doubled Northampton's lead when his 60th-minute header struck the bar, but they didn't have to wait long for a deserved second as John Johnson headed home a Ryan Gilligan corner 14 minutes later.
Veteran Delroy Facey came closest to a consolation for Lincoln when his downward header bounced over the bar.
The home side created the better chances in the opening half-hour, but wasted a string of crosses from Albert Jarrett.
Lincoln were given a let off on 34 minutes when a fierce shot from Nat Wedderburn slipped through Anyon's fingers but dropped wide.
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