Barry Corr's strike put a dent in 10-man Stevenage's play-off hopes as Southend secured a 1-0 win.
Chris Day was called into action after 12 minutes when Harry Crawford fired in a shot from close range, but the former QPR goalkeeper was equal to the challenge.
And the visitors' bid to extend their eight-match unbeaten run was thrown into doubt just before the break when Peter Winn was dismissed for a poor challenge on Sean Clohessy.
Despite being a man down, Graham Westley's men managed to steady the ship and they came out for the second half in determined mood.
Their ambition should have been rewarded when Bilel Mohsni fouled Byron Harrison in the box in the 76th minute, but John Mousinho saw his penalty pushed past the post by Glenn Morris.
And the Shrimpers claimed the points when Corr latched onto Ryan Hall's cross and blasted it home form 12 yards for his 20th goal of the season.
Source: DSG
Source: DSG