Northampton's 11-match unbeaten run was ended in emphatic fashion as Aldershot picked up only their fourth away win of the season with a comfortable 3-0 victory at Sixfields.
But Northampton can only blame themselves after handing the initiative to the visitors as Cobblers midfielder Kevin Thornton received a straight red card in the 11th minute.
The dismissal followed a bad challenge on Andy Sandell and from the ensuing free-kick Marvin Morgan headed the Shots into a 12th-minute lead.
Referee Gavin Ward struggled to keep control of the game and twice players from both sides were involved in flare ups.
Northampton threatened to get back on level terms in the second half and Luke Guttridge was denied by Stephen Henderson two minutes after the re-start after good work by substitute Liam Davis.
But Aldershot doubled their advantage in the 68th minute when substitute Kirk Hudson raced clear to finish clinically and Morgan grabbed his second in the 70th minute after taking advantage of a slip by keeper Chris Dunn.
Copyright (c) PA Sport 2009, All Rights Reserved.