Tom Hopper's close-range goal defeats Rovers at the Mem.
Southend grabbed the only goal of the game in the first half, as Tom Hopper latched onto a Theo Robinson cross to convert from close-range.
Rovers created chances - with Tom Nichols hitting the crossbar in the early stage, but Darrell Clarke's side couldn't overturn Southend's slender advantage.
In the build-up to the game, in naming his side, Manager Darrell Clarke opted to make just one change to the side that faced Portsmouth just four days prior - with Daniel Leadbitter dropping out of the starting eleven to make way for Tom Broadbent.
In what was a late change - Tom Lockyer missed out and was replaced by Leadbitter, with Michael Kelly drafted in to fill the void left on the bench.
Rovers created the first opening of the game, as Kyle Bennett looked to make full advantage of a slack pass from the Southend midfield. Bursting forward, Bennett spotted the run of Stefan Payne and looked to curl a ball into the path of the striker, but the pass had a touch too much power and was claimed by Max Oxley.
There were promising signs for Rovers in attack, as stand-in captain Ollie Clarke flighted a well-disguised pass to set Liam Sercombe on a forward run down the left. In space, Sercombe had time to lift in his head and chip a cross into the path of Tom Nichols - with the striker connecting well with a first-time attempt, but had to watch his shot bounce clean back off the bar.
As the twenty-minute mark approached, Rovers were forced into making an early change as Liam Sercombe broke down and was forced off, with Alex Rodman chosen as his replacement.
With chances few and far between in the period that followed, it was substitute Rodman that created the next spark in the game. Receiving the ball out wide, the wide-man showed a delightful piece of footwork to zip past two defenders, but as he set himself to break into the area, Rodman was tripped and the move halted.
As the halftime break loomed, it was the visitor's that made the first mark on the scoresheet, in what was a rare siege into the Rovers area. The move started down the left, as Theo Robinson squeezed a cross to the near post, that was deflected into the face of the goal by the combination of Michael Knightly and James Clarke. With the ball rebounded into a dangerous location, Tom Hopper showed the quickest reactions and swept the ball home to put Southend ahead.
It was Rovers that grafted out the first opportunity of the final forty-five minutes. In what was a tailored move that saw Rodman cut in from wide, a glimpse of a touch from Tom Nichols deflected the ball to the feet of Ollie Clarke. With space and time at his disposal, Clarke launched a powerfully struck right-footed attempt that had to be pushed wide by Oxley in the Southend goal.
Southend then created a chance of their own at the other end, as an inswinging corner caused the Rovers defence problems. Theo Robinson managed to lose his marker and glanced a header towards goal that had to be dealt with by Adam Smith.
With the final twenty minutes approaching, a double change in attack saw Gavin Reilly and Alex Jakubiak introduced, as Tom Nichols and Stefan Payne made way.
With Southend intent on slowing the play down at every opportunity, it proved difficult for Rovers to maintain any momentum. James Clarke made the noise levels inside the Mem rise when he set off on a meandering run forward that took the defender deep into the final third. With a number of players on his tail, Clarke was purposefully tripped and the chance to hit the visitors on the break ceased.
With Rovers committing more men forward - Southend looked to punish the home side the break. Simon Cox took advantage of such opportunity, purposing forward and finding Graham McLaughlin. It was McLaughlin's cross that etched its way to Hopper at the far-post, but the striker couldn't adjust in time to nod the ball goalwards.
Inside the final ten minutes - a driving run forward from Rodman saw the winger cut inside the area, but as he shifted his body to forge a shot, he was squeezed away from goal.
Rovers XI: Adam Smith (GK), James Clarke, Daniel Leadbitter, Tom Broadbent, Tony Craig, Ollie Clarke, Ed Upson, Liam Sercombe (18' Alex Rodman), Kyle Bennett, Tom Nichols (67' Gavin Reilly), Stefan Payne (67' Alex Jakubiak).
Unused Subs: Alexis Andre-Jr (GK), Michael Kelly, Luke Russe, Alex Rodman, Bernard Mensah, Gavin Reilly, Alex Jakubiak.
Southend XI: Mark Oxley (GK), Elvis Bwomono, Ben Coker, Michael Turner, Michael Kightly, Tom Hopper, Stephen McLaughlin (85' Stephen Hendrie), Sam Mantom, Jason Demetriou, Theo Robinson (77' Simon Cox), John White.
Unused Subs: Simon Cox, Nathan Bishop, Michael Klass, Harry Kyprianou, Shawn McCoulsky, Stephen Hendrie, Lewis Gard.