FREDDY Eastwood did what has done for many years to poach the only goal in yet another infuriating day at the office for United.
The Gulls matched Southend throughout but could not hit the net, and when the home side introduced their experienced striker for the closing 20 minutes, it proved decisive.
United manager Chris Hargreaves made three changes from the midweek loss at York and they were all in attacking areas. Jayden Stockley and Karl Hawley were the chosen strike-force ahead of Elliot Benyon and the departed Enoch Showunmi.
Courtney Cameron returned from injury to take his place on the wing, with Niall Thomson dropping out of the squad. New loan signing from Tottenham, Shaquile Coulthirst, was the intriguing striker option on the bench.
Unsurprisingly, Southend boss Phil Brown stuck with the same side that trounced Oxford 3-0 on Monday night. The only tweak came among the substitutes, where Jacob Murphy replaced Connor Clifford.
The frightening pace of Southend’s Jamar Loza immediately came to the fore, as the youngster on loan from Norwich took a chance to run at Aaron Downes and his driven delivery was well held by goalkeeper Martin Rice.
The focus on attacking United’s left side continued with another surge from Loza but Kevin Nicholson produced a solid tackle to halt the progress, and when the ball was eventually hoisted into the box, Rice again showed handling.
United responded with a fabulous cross from Cameron after Lee Mansell had spread the ball wide and the Shrimpers were at full stretch to clear at the far post. From the next Yellow attack, it should have been the opening goal.
Stockley picked up a deep free-kick from Nicholson and cut inside for shot of his left-foot. Southend managed to clear off the line but the rebound fell to Mansell, who will be disappointed to have lashed his shot wide from 12 yards.
United were causing their hosts real problems and the combination of Billy Bodin and Cameron had the Shrimpers momentarily bamboozled, but a touch too many from the Gulls allowed Joel Egan to clear.
The first corner of the afternoon produced an incredible miss from Southend. Defender Jacob Sokolik came steaming in at the back post and somehow scooped the ball over the bar from no more than a yard out.
It was a horrendous moment for Sokolik and John White tried to spare his team-mate’s blushes with a decent strike from distance that flew narrowly over. The home pressure continued with a superb piece of skill and cross from Loza, but Lee Barnard was unable to convert at the back post.
A nasty challenge from Will Atkinson on the half-hour left Nicholson horizontal on the deck and the home winger was very lucky to escape a booking from referee Scott Mathieson.
A dazzling run from Cameron exposed Southend from the next attack and the cross toward Stockley needed the intervention of Sokolik to prevent a header on goal to test home goalkeeper Daniel Bentley.
United then had a major concern over Cameron, who had picked up an earlier caution and Southend were looking to wind up the youngster with a tussle from White, but the referee was content with a lecture and not what would have been a crushing dismissal.
The Shrimpers quickly stormed forward with another dangerous cross in the box but well defended by the Gulls. A foul by Krystian Pearce then offered Southend a chance to shoot from distance but Ben Coker could only hit the wall.
The first half ended with Loza breaking into the box and Yellow hearts were in Yellow mouths when Downes launched into an awkward challenge, but the mild penalty claims were waved away. United still had time for Bodin to find room in the box but Mathieson ignored another penalty shout.
Michael Timlin had the last chance of an entertaining 45 minutes and it needed alert goalkeeping from Rice to keep the scores level for a massively important second half of football.
The officials were straight back into action after the restart, as Stockley was fouled off the ball and Cameron then taken out on the edge of the area.
After a chat with his assistant, Mathieson showed Sokolik, White and Stockley a yellow card each. Eventually, the free-kick was taken by Stockley, who cleared the bar.
United continued to play the brighter football and Southend were struggling to contend with the partnership of Stockley and Hawley, but the elusive goal was becoming increasingly essential.
The Gulls were then guilty of completely falling asleep from a throw-in and Barnard had a glorious chance, but Rice conjured up an excellent save. The subsequent corner was headed against the bar by White and a massive escape.
Southend were cranking up the pressure and fine work from Kevan Hurst created space again for Barnard, who flicked the outside of Rice’s post with his instant shot.
Hargreaves decided the time was right to introduce Coulthirst, removing Stockley in a change of attacking emphasis. The Shrimpers also made a switch, bringing on Jacob Murphy for Timlin. Eastwood replaced Barnard moments later.
The Gulls were grateful to Mansell for pressuring Hurst into a shot dragged wide from Southend’s next attack but there was no doubt the home side were looking to increase their tempo.
It turned out to be Eastwood who would make the crucial difference, pouncing on a loose header from Ben Harding and the ball was perfect for Loza to drill the back across for the experienced striker to convert.
Cameron was immediately removed for the fresh legs of Jordan Chapell but Eastwood was a real menace at the other end, and the Gulls needed a fine recovery challenge from Downes.
Coulthirst tried to show his worth in a swift riposte but the youngster was crowded out by the home defence after clever work to initially find some space. O’Connor then whipped in a cross for Coulthirst but Sokolik just managed to deflect the header wide.
United were in a position where the need for a goal was beyond desperate and a decent response to going behind gave the travelling Yellow Army some hope for the final 10 minutes.
Marc Laird replaced Loza in a clear protective move from Southend, while Hargreaves understandably went for an attacking switch, introducing Ashley Yeoman for Hawley.
The Shrimpers were more than happy to eek away at the clock and the frustration for United merely grew with every passing second. It was strong and sensible work from the home side, but painful for the Gulls.
Five minutes of injury time gave United some last-gasp hope and a cross to the far post from Chapell was headed a fraction wide by Mansell.
Another opportunity had slipped by and United had to trudge all the way back to Devon with the knowledge that we now probably need to win five of the last six games to survive.
Southend [4-4-2]: 17 Daniel Bentley; 2 John White, 35 Jacob Sokolik, 32 Joel Egan, 3 Ben Coker; 14 Kevan Hurst, 8 Michael Timlin [15 Jacob Murphy 61], 18 Ryan Leonard, 12 Will Atkinson; 9 Jamar Loza [4 Marc Laird 83], 39 Lee Barnard [7 Freddy Eastwood 65]. Substitutes [not used]: 1 Paul Smith [GK], 6 Luke Prosser, 11 Anthony Straker, 21 Jack Payne.
Booked: Sokolik 48, White 48, Loza 79
United [4-4-2]: 13 Martin Rice; 29 Anthony O’Connor, 5 Krystian Pearce, 4 Aaron Downes, 3 Kevin Nicholson; 10 Billy Bodin, 7 Lee Mansell [capt], 8 Ben Harding, 11 Courtney Cameron [12 Jordan Chapell 74]; 9 Karl Hawley [14 Ashley Yeoman 85], 19 Jayden Stockley [27 Shaquile Coulthirst 60]. Substitutes [not used]: 1 Michael Poke [GK], 2 Dale Tonge, 6 Damon Lathrope, 26 Elliot Benyon.
Booked: Cameron 33, Stockley 48, O’Connor 71, Harding 73
Referee: Scott Mathieson
Attendance: 6,393 [163 away].