Leading 2-0 at half-time through majestic goals from Nathaniel Clyne and Rickie Lambert, the hosts appeared to have nullified the threat of their Championship opponents, but a quick-fire start to the second 45 from Burnley ensured there was a real fight to the cup tie.
The Clarets’ in-form strikers Sam Vokes and Danny Ings, each struck within quarter of an hour after the restart to level the contest up, which prompted changes from Mauricio Pochettino to rescue the tie.
Former Burnley man Jay Rodriguez, who was brought on in the first half in place of the injured Lambert, restored Southampton’s lead with a routine finish, but it was the introduction of Adam Lallana that made sure of the success as the midfielder scored on 73 minutes to regain Saints’ two-goal lead in the game.
Burnley managed to find a late consolation through defender Kevin Long to make it a slightly nervy end to the contest, but Saints held out to maintain their one hundred per cent record over the Clarets in this competition.
Pochettino made five changes from the team that started against Chelsea in midweek. Jose Fonte, Dejan Lovren, Calum Chambers, Jay Rodriguez and Adam Lallana all dropped out of the starting eleven, with Clyne and Lambert amongst those restored to the side.
Kelvin Davis kept his place in goal, and he captained the team once more on his 291st appearance for the club.
Burnley got the tie underway, dressed in their changed strip of all white with claret and blue socks, attacking the Chapel stand on a drizzly afternoon at St Mary’s.
The visitors - flying high in the Championship - named a strong team, with an attacking line led by Hampshire pair Vokes and Ings, who were both keen to impress against their boyhood club.
The Clarets settled quickly, and got their first effort of the game in with less than two minutes on the watch when winger Scott Arfield cut inside from the right flank to strike a curling effort narrowly wide of Kelvin Davis’s left post as Saints were given an early let-off.
Despite the damp conditions, both teams stuck to their principles of playing neat and tidy possession football where possible, to try and force an opening.
Gaston Ramirez was the first Saint to test Tom Heaton in the Burnley goal when he collected a pass from Steven Davis before spinning to shoot low towards the bottom left corner, but the weak effort was easily saved.
Saints were bright going forward, with Clyne and Shaw supporting the attack to good effect to deliver some telling crosses, but it was very much an even contest inside the first 15 minutes or so, with Ings getting a header in at goal that Davis collected just under his crossbar.
At the other end, Ramirez put over a dangerous looking cross from the left which had to be headed out by Danny Lafferty at the far post as Saints came back into the contest.
The game burst into life with that little bit of magic that the cup can often bring in the 22nd minute. CLYNE was the scorer as he notched his second goal for the club, and in some style, too. The full-back collected Cork’s pass and with the ball sitting up nicely on the edge of the area, he swung a stunning shot from the right flank into the top corner of Heaton’s goal for 1-0.
Cries of ‘shoot’ followed each time the right back touched the ball in the minutes following that strike, as the home side pushed on in search of a second goal.
It duly arrived in the 28th minute, but this time in more familiar circumstances. A fine piece of link-up play involving Ramirez and Steven Davis saw the ball played into the path of LAMBERT, who hit a crisp finish into the far corner that Heaton had no chance of getting to.
At 2-0, the contest appeared comfortable for the hosts, and they had a good opportunity to make it 3-0 on the half hour when Ramirez headed down Clyne’s cross into Lambert, but the striker couldn’t keep his shot down, as the ball flew over the bar.
Burnley were awarded a free-kick which Kieran Trippier drilled into the wall, with James Ward-Prowse making the telling block.
Saints were forced into an earlier than planned substitution when Lambert sadly had to limp out of the action with a knock he sustained to his hip earlier on in the game. Former Claret Jay Rodriguez took the frontman’s place in attack.
The hosts maintained their attacking intent, with a string of neat passes that frustrated the visitors, who were unable to break down Saints.
Buoyed by their lead, the home side continued to search for goals, and inside the final five minutes of the half Luke Shaw drilled in a low shot at the near post, which Heaton did well to put out for a corner.
The whistle for half-time sounded with Saints looking good value for their lead, with one foot in the next round already.
HALF-TIME: SOUTHAMPTON 2-0 BURNLEY
There were no changes from either side at the break, as Saints got the action started again defending the Northam stand.
And with less than five minutes into the second half, the Clarets drew level through Sam VOKES as the visitors’ frontline combined to cut the deficit in half. The Welsh forward headed home a cross from Danny Ings’ right sided cross from eight yards out to make it 2-1.
Kelvin Davis was called upon to make a low save soon after, and Burnley further tested the hosts when Vokes met a cross from Trippier which he headed onto the roof of the net
Saints eventually drew a response when Rodriguez fired in a shot from the left that Heaton had to smother.
But Burnley battled on, and they got the reward they craved when INGS fulfilled his lifelong dream by scoring at St Mary’s. He got the better of Hooivled with a strong run into the box from the right, and then kept his composure at the near post to fire a shot across Davis into the far corner for 2-2.
An incredible turnaround was nearly completed when Vokes forced his way through into the middle of the area and brought a terrific save from Davis, whose one-handed block denied the frontman from doubling his tally in the game.
With Saints now on the ropes, Adam Lallana was brought on in place of the injured Ramirez, as the hosts searched for a way back.
Rodriguez then had another opportunity when he shrugged off Kevin Long’s advances to fire in a shot at Heaton, with the true cup tie nature to the match now fully restored.
Burnley made their first change with Junior Stanislas replacing Keith Treacy with as the visitors looked to the pace of their substitute for further inspiration in the final half hour.
However, the hope was short-lived as Saints retook the lead with 66 minutes on the watch. Steven Davis played Ward-Prowse in on goal, where a smart block from Heaton denied the youngster from snaffling a close range finish, but the ball broke back kindly for RODRIGUEZ who made no mistake as he passed the ball into the net from the edge of the area for 3-2.
Burnley almost came back again when Stanislas played the ball into the area on 71 minutes and Ings struck the post from close range as Saints breathed a sigh of relief.
And, in an instant, the game was over on 73 minutes with the hosts finally silencing the Clarets through a strike of sheer quality. Skipper Adam LALLANA picked up the ball in the Burnley half and hit a 25 yard strike into the bottom right corner for the game’s sixth goal, to make it 4-2.
The visitors worked hard to try and get back in the game again with Ings a constant threat, and his increasing presence prompted a final change from the hosts with Jose Fonte replacing Hooiveld with just over ten minutes to play.
With Rodriguez chasing a second goal of the game, he saw a shot deflected out for a corner which resulted in Fonte getting his first touch on the ball as the defender rose highest to meet Ward-Prowse’s delivery from the set-piece, but Heaton was able to claim.
On 83 Rodriguez went even closer as he picked up Steven Davis’s cute dinked pass into the box, but Heaton was quickly off his line to thwart the danger, with time running out for any further goals.
But, there was a seventh goal of the game on 86 minutes. Shortly after Ings had tested Davis with a low shot, Burnley struck again from the resulting corner. The high, hanging delivery landed on the head of defender Kevin LONG who nodded in from close range to make it 4-3.
Vokes had a chance in the 89th minute when he bore down on Davis’s goal after a mix up from Clyne and Steven Davis, but his tame shot was comfortable for the Saints keeper.
The hosts played possession football which resulted in Rodriguez curling an effort wide, and with four minutes of stoppage time allocated, Saints had to withstand some heavy pressure late on, but they held out to progress in the competition at the Lancashire side’s expense.
FULL-TIME: SOUTHAMPTON 4-3 BURNLEY
Southampton team: Kelvin Davis (c), Nathaniel Clyne, Maya Yoshida, Jos Hooiveld (Jose Fonte 79), Luke Shaw, Jack Cork, Morgan Schneiderlin, Steven Davis, James Ward-Prowse, Gaston Ramirez (Adam Lallana 59), Rickie Lambert (Jay Rodriguez 36)
Unused substitutes: Paulo Gazzaniga, Calum Chambers, Harrison Reed, Sam Gallagher
Goals: Clyne (22), Lambert (28), Rodriguez (66), Lallana (73)
Burnley team: Tom Heaton, Kieran Trippier, Danny Lafferty, Jason Shackell (c), Kevin Long, David Jones, Dean Marney, Keith Treacy (Junior Stanislas 63), Scott Arfield, Danny Ings, Sam Vokes
Unused substitutes: Alex Cisak (GK), David Edgar, Luke O’Neill, Brian Stock, Steven Hewitt, Cameron Dummigan
Goals: Vokes (50), Ings (57), Long (86)
Referee: Robert Madley
Attendance: 15,077 (including 845 away)