Blues were soundly beaten 4-0 by Plymouth Argyle at Home Park with Ruben Lameiras and Graham Carey grabbing two goals each.
Southend were on the back foot almost immediately as Argyle took the lead inside three minutes with Lameiras calmly slotting the ball home after a cut-back from Ryan Taylor.
Blues then had two glorious chances when Anthony Wordsworth missed from a tight angle before Simon Cox had an opportunity minutes later after Dru Yearwood’s strike was fumbled in the area.
Argyle immediately made Southend pay for their profligacy in front of goal as Carey grabbed his first of the game via a huge deflection off the unfortunate Sam Mantom.
Carey made the points all but safe early in the second-half when he grabbed his second just seven minutes after the interval but he missed the chance to claim his hat-trick by missing a penalty late on.
Lameiras though would round off the scoring with two minutes remaining as he reacted first to a loose ball inside the area to tap home Argyle's fourth.
The win for Argyle saw them leapfrog Peterborough to return to the play-off places while Southend’s very slim chances of getting into the top-six suffered a potentially knock-out blow.
Chris Powell was wary of the fact that his Blues side might see a reaction from Plymouth following Argyle’s defeat to Charlton Athletic last weekend and that's exactly what they were greeted with on their first visit to Home Park since 2014.
Blues had headed to Devon in confident fashion following last weekend's win over Rotherham and Powell made just the one change following that win against the Millers with Jason Demetriou returning to the back-line in place of Elvis Bwomono.
Their hosts Plymouth also made one change from last Saturday with Sonny Bradley coming into Derek Adams’ side and the home team made a lightning quick start as they took the lead inside the opening three minutes.
Ryan Taylor and Ruben Lameiras had already linked well in the opening minute to carve out a chance before they combined once more to open the scoring with Taylor’s cut-back being calmly stroke home by Lameiras to give Argyle the lead.
Having gone behind so early, Southend responded well and had two glorious chances to level in quick succession through Anthony Wordsworth and then through Simon Cox.
Wordsworth’s chance came when Jason Demetriou’s cross from the right was flicked onto the far post by Bradley, falling to the Blues midfielder who couldn’t find the target from a narrow angle.
And moments later a strike from Dru Yearwood was fumbled into the path of Cox by goalkeeper Remi Matthews, but the striker couldn’t connect with the rebound as Argyle’s lead remained intact.
Even just half an hour into the game it was looking like being one of those days for Blues, having missed those two golden chances in front of goal, and their luck in the first-half was summed up by Argyle’s second which came mere seconds after Cox had missed his opening.
Graham Carey cut in from the right-hand touchline and let fly from distance as orange shirts descended on him to try and block the strike. His effort though would take a wicked deflection off Sam Mantom and loop up and over Oxley to extend the home side’s lead.
Just before the break, Southend felt they should have been given a lifeline after Taylor appeared to clash with Michael Turner with a flailing arm – the referee, however, felt the contact was only worth a yellow card as the half-time whistle blew.
The next goal in this game was going to be crucial and Southend knew they needed to get it if they had any chance of salvaging anything from their trip to Devon.
But hopes of even a point were all but quashed when Argyle strengthened their grip on the points after Oscar Threlkeld’s cross found its way to Carey who powered the ball home to make it 3-0.
With Carey now on the hat-trick, the Argyle number 10 went close to claiming his third with a well-struck free-kick that had to be parried away by Oxley and he had an even better chance with 20 minutes of the game remaining after Argyle were awarded a penalty.
Substitute Joel Grant was adjudged to have been brought down inside the area by John White, allowing Carey a perfect chance to claim the match ball but he failed to find the target from 12-yards, striking the top of the crossbar with his spot-kick.
Argyle though would round off an afternoon to forget for Blues with a fourth two minutes from the end through Lameiras. The Argyle number 11 was quickest to react after Grant's effort was saved by the feet of Oxley, leaving Lameiras the simple task of tapping the ball home.
Plymouth Argyle XI: Matthews, Sawyer (C), Ness (Taylor-Sinclair 82’), Carey, Lameiras, Makasi, Bradley, Threlkeld, Taylor (Grant 71’), Vyner, Fox (Songo’o 75’). Subs Not Used: Letheren, Ainsworth, Paton, Sangster
Blues XI: Oxley, Coker (C), Wordsworth (Wright 75’), Turner, Fortune (Kightly 57’), Cox (Robinson 78’), McLaughlin, Yearwood, Mantom, Demetriou, White. Subs Not Used: Bishop, Ferdinand, Timlin, Harrison
Referee: Brendan Malone
Assistants: Ronald Ganfield & Robert Dabbs
Fourth Official: Mark Pottage
Plymouth Argyle: Ruben Lameiras 3’, 88', Graham Carey 34’, 52’
Southend United: None
Plymouth Argyle: Ryan Taylor 45+2’
Southend United: Anthony Wordsworth 42’