The Blues let the lead slip twice as they dropped two vital points in a 2-2 draw at home to Northampton Town.
After both sides went close inside the first two minutes Jermaine McGlashan opened the scoring after tapping home from close range after a scramble in the area.
Northampton responded by equalising less than 10 minutes later as the ball fell to Marc Richards on the edge of the area to curl the ball into the back of the net.
Southend went back in front almost immediately as Jason Demetriou’s shot was deflected towards Simon Cox who instinctively found the bottom corner.
But the Cobblers would find an equaliser before the interval after Matty Taylor’s free kick came off the post, hit the back of Ted Smith and was bundled over the line by John-Joe O’Toole.
The second half failed to live up to the back-and-forth action of the first, but Nile Ranger had two great chances to grab the Blues a winner after being introduced as a sub.
The Blues number 50 rose brilliantly to head on goal only for Adam Smith to tip his effort over the bar before Zander Diamond was on hand to hack Ranger's effort away after he broke clear.
And in injury time Theo Robinson had a great chance to snatch Southend then win as he got on the end of a Ranger knock down only to shoot wide.
Blues Boss Phil Brown will be disappointed not to have grabbed all three points with a number of other sides in and the around the play-off places dropping points as well.
Confidence in the camp at Roots Hall was high after their 2-0 win away at Oxford United and Brown named an unchanged side to that that won at the Kassam.
The Blues almost made the perfect start at Roots Hall as Marc-Antoine Fortune was found at the far post by a cross from Ben Coker but the striker failed to find the target with his header.
Northampton then went straight up the other end and went close themselves as the experienced Matty Taylor let fly from over 30-yards with his strike whistling past Ted Smith’s left-hand post.
After the early chances for both sides the game simmered down until Phil Brown’s side took the lead after 20 minutes through Jermaine McGlashan.
The overlapping Coker played the ball into the area only for Simon Cox to completely miss the ball, and after a scramble in the six-yard box McGlashan came storming in to tap Southend in front.
Southend’s lead though lasted less than 10 minutes as Justin Edinburgh’s side equalised through their captain Marc Richards just before the half hour mark.
Taylor did brilliantly well to keep the ball in play and get a cross into the box, and after the ball fell to Richards on the edge of the area the front-man found the back of the net with a curling effort.
The Blues had gone into the game with just two defeats in 19 league games and they reacted in the best way possible by immediately going back in front.
Jason Demetriou cut inside from the right to take a shot with his left foot which deflected into the path of Cox. The striker instinctively shot first time and found the bottom corner despite the best efforts of goalkeeper Adam Smith who got a big hand to the ball.
It was the perfect response from Phil Brown’s Blues and Smith was on hand to stop Cox from grabbing Southend’s third of the game as he parried a shot away from the Blues number 10.
The save proved a vital one as Northampton managed to get themselves level again on the stroke of half time as Taylor’s free-kick came off the post, hit the back of Smith and was bundled over the line by John-Joe O’Toole.
Southend still had time to almost swing the advantage back their way at the end of a pulsating half of football as Anthony Wordsworth’s free kick looked destined for the top corner only for the hand of Smith to parry it away.
The pace of the game continued into the second half as Richards had a couple of early opportunities for the Cobblers to go in front for the first time in the match but both went wide of the target.
Southend were being put under a fair amount of pressure by their visitors and Brown chose to change things up just after the hour as both Nile Ranger and Theo Robinson were introduced.
The Blues had failed to get going in the second half but the introduction of the two front-men seemed to spark them to life and Ranger came ever so close to putting Southend back in front as his header had to be tipped over superbly by the fingertips of Smith.
Ranger was then denied again minutes later as he managed to get in a shooting position inside the penalty area. The substitute’s effort beat the advancing Smith but had to be hooked clear by the retreating Zander Diamond.
Both sides had six minutes added on time to grab a winner and Southend went so close to scoring the game’s fifth and vital goal as Ranger headed the ball down for Robinson only for him to shoot wide.
Blues XI | Smith, Coker, Wordsworth, Thompson, Timlin, Cox, Fortune (Robinson 62’), McGlashan (Ranger 62’), Leonard, Demetriou, Ferdinand (C)(Inniss 70’). Subs Not Used: O’Neill, Amos, Nouble, Bexon
Northampton XI | A Smith, Buchanan, Diamond, Boateng (McCourt 62’), Richards (C), Wylde (P Anderson 62’), O’Toole, Nyatanga, M Smith, Taylor, Eardly. Subs Not Used: Zakuani, K Anderson, Beautyman, Phillips, Cornell
Referee: John Brooks
Assistants: Nicholas Cooper & Ashvin Degnarain
Fourth Official: Ian Cooper
Southend United: Jermaine McGlashan 20’, Simon Cox 31'
Northampton: Marc Richards 29’, John-Joe O’Toole 44’
Southend United: Ben Coker 51’, Jason Demetriou 83’
Northampton: Neal Eardley 45’, Lewin Nyatanga 45’, Michael Smith 77’, Zander Diamond 90’