Saints came through a potentially awkward evening against Championship strugglers Barnsley with assurance, scoring four times in the second half to seal progression in the cup competition.
The visitors led 1-0 at half-time through a well-taken strike from Steven Davis which broke the deadlock after 26 minutes of play.
Jay Rodriguez added a second just four minutes into the new half, but a twist arrived when Tykes skipper Stephen Dawson cracked home an impressive strike to make it 2-1 before the hour mark.
The win looked safe when Emmanuel Mayuka struck his first competitive goal for the club by swinging a fierce strike into the top right corner for 3-1 on 66 minutes.
It was the two late strikes either side of the 90th minute though which added gloss to the success as Davis netted another, this time from the spot after Mayuka was brought down inside the area, before Ramirez settled the scoring with a neat finish.
There were further reasons to cheer as Mauricio Pochettino also handed senior debuts to three Saints Academy products late on as Omar Rowe, Harrison Reed, and Jake Sinclair all got a taste of the action, with Southampton making it a fourth consecutive win against the Tykes in all competitions, and maintaining their 100% record over the Tykes in League Cup action.
Saints made nine changes to the starting line up from the team that drew 1-1 with Sunderland in the Barclays Premier League on Saturday.
Only Jose Fonte and Jay Rodriguez kept their places as Mauricio Pochettino took the opportunity to rotate his squad of players and give opportunities to those who hadn’t featured in the league action so far.
Welsh Under-21 winger Lloyd Isgrove was handed his first start for Saints in a senior role, whilst Development Squad members: Harrison Reed, Jake Sinclair and Omar Rowe was amongst the seven man substitutes’ bench.
Saints got the match underway lining up in their new black and white strip for the first time in a competitive outing, with the travelling support behind Kelvin Davis’s goal for the opening 45 minutes.
The visitors had a glorious opportunity to open the scoring inside the first minute of action when Rodriguez played Ramirez into the Barnsley area, but with ‘keeper Mike Pollitt approaching, the Uruguayan dragged his shot wide as he aimed for the far post.
In the fifth minute, Ramirez whipped a tidy delivery from a free-kick on the left into the area, with Yoshida going closest to taking the vital touch, but not getting close enough to divert the ball past Pollitt.
The game opened out as Barnsley began to venture forward, but Saints remained the more comfortable side in possession as they were happy to build from the back when possible. One such move saw Fox get down the left to swing in a cross to the far post which Pollitt got his hands to, but despite letting the ball slip out of his hands, Rodriguez couldn’t quite apply the finish from close range.
The hosts created their first real opportunity in the 18th minute when a long punt down field was flicked on by Chris O’Grady and into the path of fellow striker Marcus Pederson whose shot at goal had Davis scrambling, but the ball just dropped wide of the left post.
On 21 Ramirez forced a corner off Jimmy McNulty as the number 10 raced to meet Fox’s cross. How the opportunity came about though, owed much to the persistence of Clyne, who carried the ball from right to left
Saints broke the deadlock in the 26th minute with a powerful finish from Steven DAVIS. The Northern Irishman played a one-two with Isgrove before setting himself to strike low into the bottom left corner for 1-0.
From there, the visitors looked likely to build on their advantage. Just past the half hour, a silky link up on the left resulted with Rodriguez lifting the ball into Cork’s path, but the first time effort from the midfielder went into the side-netting.
Pederson attempted to level up for the hosts with an ambitious drive from range, but again he was off-target as Davis remained largely untroubled.
Rodriguez forced a low save from Pollitt going into the last ten minutes of the half, with Scott Wiseman on hand to avert the danger before Mayuka chased the rebound.
The chances kept on coming for Saints, and on 40 Ramirez almost produced a breath-taking finish when he guided Fox’s cross into the far corner with a delicate chip, but the ball landed just the wrong side of Pollitt’s left post.
The Tykes came close to working Kelvin Davis in the closing stages of the half, but former Saints loanee Jacob Mellis hit a rising drive just wide of the near post.
Despite some late attempts from the hosts to break forward, including a free-kick from Jim O’Brien which went all the way through the area, Saints remained in control going into the half-time break.
HALF-TIME: BARNSLEY 0-1 SOUTHAMPTON
Barnsley got the second 45 underway, but the contest picked up from where it left off with Saints posing an initial threat. Another pinpoint pass from Fox released Rodriguez, who turned the last defender before shooting narrowly wide.
Isgrove then injected a fresh burst of pace to earn the visitors a corner, and before the clock had reached 50 minutes, Saints went 2-0 up.
A swift break forward involving Steven Davis and Jack Cork led to the ball finding its way to Jay RODRIGUEZ, who curled a sublime finish into the bottom right corner which Pollitt had no chance of keeping out.
The former Burnley man almost grabbed a quick-fire second just two minutes later when he collected an airborne pass on his chest before getting the ball out of his feet to strike a low shot off the post.
Out of the blue, Barnsley cut the deficit in half on 53 minutes when a thunderbolt from Tykes captain Stephen DAWSON fully 25 yards out, flew into the net past Kelvin Davis
Sensing an opportunity to catch Saints again, the hosts swiftly followed up with a double substitution as Pederson was replaced by Jason Scotland, whilst Tom Kennedy made way for Chris Dagnall.
The changes lifted the spirits amongst the home faithful who were desperate to see their side get back into the game, and the impact from Dagnall in particular ought to have yielded more when he found space inside the area, but he couldn’t control the ball quickly enough to seriously test Davis.
On the hour mark, Ramirez made a break for goal, but was brought to ground before he could get his shot away. He dusted himself down to take the resulting free-kick, which whistled just over the crossbar with Pollitt left rooted to his spot.
Rodriguez attempted an acrobatic finish from a Ramirez corner before Barnsley almost scored again when Scotland’s neat lay-off to Mellis saw the midfielder pull the trigger once again, but his volley went wide of Davis’s right post once more.
The Tykes were forced to replace the injured Kelvin Etuhu with Tomasz Cywka on 65 minutes, and almost immediately afterwards Saints went 3-1 up.
The ball was played in from the right where MAYUKA took one touch to control the ball before unleashing a fierce strike into the top right corner. The goal sparked a wild celebration from the 695 travelling fans as well as the Zambian, who back-flipped his way over to greet his supporters.
Ramirez attempted a spectacular effort which was held by Pollitt before Saints handed out another debut, as Saints Academy star Omar Rowe replaced Isgrove in the 71st minute.
Rowe took straight to the rhythm of the game, playing a one-two with Ramirez and setting on a direct run into the box where his cut-back was unfortunately intercepted by a red shirt.
Saints briefly weathered another storm before taking full command of the contest, with Yoshida adding a calm nature to the defending, even bringing the ball out into the attacking half of the field.
Harrison Reed was the next young Saint to get a taste of the action. The midfielder, who signed a new contract with the club on Saturday, replaced goal scorer Rodriguez for the final ten minutes.
After Ramirez had blazed over from another free-kick, Saints could have gone 4-1 up when Steven Davis burst through and unselfishly laid the ball into the path of Rowe, but the low shot from the young winger was kept out by the legs of Pollitt.
Barnsley attempted to rally late on, but the final nail in the coffin was placed when Mayuka was brought to ground inside the area as he attempted to convert Reed’s cross.
Mayuka gingerly got back onto his feet, as Steven DAVIS added another to the scoresheet in the 89th minute scoring with a well struck spot-kick to the right of Pollitt which although the ‘keeper stuck a hand to, could not prevent from going in.
Mayuka was then replaced by Academy striker Jake Sinclair as three minutes of stoppage time went up on the board, but the scoring was not done there.
RAMIREZ saved the best until last by skipping his way through on the right hand side of the area before clipping a fine low finish at the near post into the net for 5-1.
Omar Rowe tested Pollitt again at the death, with the whistle sounding to see Saints settle for five.
FULL-TIME: BARNSLEY 1-5 SOUTHAMPTON
Barnsley team: Mike Pollitt, Scott Golbourne, Tom Kennedy (Chris Dagnal 54), Jim O’Brien, Stephen Dawson, Scott Wiseman, Jimmy McNulty, Jacob Mellis, Marcus Pederson (Jason Scotland 54), Chris O’Grady, Kelvin Etuhu (Tomasz Cywka 65).
Unused substitutes: Luke Steele, Paddy McCourt, Reuben Noble-Lazarus, Dale Jennings
Goal: Stephen Dawson, 53
Southampton team: Kelvin Davis (c), Nathaniel Clyne, Jose Fonte, Maya Yoshida, Danny Fox, Jack Cork, Steven Davis, Lloyd Isgrove (Omar Rowe 71), Gaston Ramírez, Jay Rodriguez (Harrison Reed 80), Emmanuel Mayuka (Jake Sinclair 90).
Unused substitutes: Paulo Gazzaniga, James Ward-Prowse, Calum Chambers, Jack Stephens
Goals: Steven Davis, 26 & 89 (pen); Jay Rodriguez, 49; Emmanuel Mayuka, 66; Gaston Ramirez, 90
Referee: Scott Duncan
Attendance: 6,574 (including 695 away)