Two early goals from Kane Ferdinand gave Southend victory at Roots Hall.
Ferdinand should have scored before he put the Shrimpers ahead on seven minutes, heading over from six yards from the first of many Ryan Hall crosses.
It was from a Hall free-kick that Paul Sturrock's side gained the advantage on seven minutes, Ferdinand heading in and the midfielder soon added a second, his far post header from another Hall cross evading Scott Loach in the Town goal after appearing to take a deflection off Luke Chambers.
Blues responded with a Josh Carson right foot effort that brought a first save from 'keeper Daniel Bentley. Jay Emmanuel-Thomas' deep cross drifted past Michael Chopra at the far post, Emmanuel-Thomas then firing over from the edge of the box.
Neil Harris came close to adding a third with a header from yet another Hall delivery as Southend threatened a third. Blues enjoyed plenty of possession in the first-half but failed to really test Bentley in the home goal, Andy Drury failing to get any power with an effort just before the break, while Carlos Edwards' cross after an incisive Massimo Luongo pass slipped past everyone to safety.
Ryan Stevenson replaced Drury as the second-half got underway, Luongo bringing a save from Bentley inside 60 seconds, while at the other end it took a timely challenge from Chambers to deny Gavin Tomlin.
Ryan Cresswell hacked an Aaron Cresswell cross over his own bar from five yards out and from the resultant corner, Stevenson was denied by Bentley after Anthony Straker had cleared off the line.
Luongo weaved his way past two defenders but couldn't make it count as Town carried a far greater threat than in the opening half but the deficit was reduced in bizarre circumstances when Mark Phillips' backpass was missed by Bentley and ended up in the net.
Jimmy Bullard replaced Luke Hyam before the restart and two minutes later Stevenson rattled the bar from 20 yards as Town pressed for an equaliser.
Bentley made amends for his error with a smart save from Chopra after the Town frontman had spun away from his marker, Bullard firing wide as the game entered the last 10 minutes.
Emmanuel-Thomas was inches away from an equaliser with a left foot curler but Southend held on for the victory.
Town: Loach, Edwards, Chambers, Delaney, Cresswell, Emmanuel-Thomas, Luongo, Drury (Stevenson 46), Hyam (Bullard 70), Carson, Chopra. Subs not used: Lee-Barrett, Ainsley, Scotland, Murray, Kourouma, Whight.