Watch the EFL LIVE on beIN SPORTS | Sign up to take advantage of our 7-day free trial | AU | NZ

Russell Martin’s Saints were in desperate need of a morale-boosting win having lost four of their five games in all competitions since a club-record 25-match unbeaten run came to an end.

Birmingham threatened to further dent their fading automatic promotion bid, but Southampton’s strong bench and unwavering spirit paid dividends as substitute Aribo struck deep in stoppage-time.

It was a blockbuster end to a breathless encounter that began with Koji Miyoshi putting the Blues ahead inside two minutes, only for Adam Armstrong to deservedly level for the Saints.

But Birmingham caught the visitors out and Jay Stansfield put it back ahead against the run of play, meaning the Saints had to rally after the break.

David Brooks scored a brilliant equaliser and Che Adams put Martin’s men ahead, with Blues skipper Dion Sanderson’s sending-off appearing to end this clash as a contest.

Further twists followed, though, as Birmingham, fighting for absent boss Tony Mowbray, levelled through Juninho Bacuna, before Aribo snuck Southampton a potentially huge stoppage-time winner at St Andrew’s.

This clash was a wild ride from the start, with Bacuna’s fine ball putting Miyoshi all too easily in behind to send an effort whizzing past Gavin Bazunu via a Ryan Manning deflection.

The 26-year-old appeared to handle in the build-up, but the goal stood and Birmingham nearly had a quickfire second, with Bacuna’s strike hitting a post and then going out off the back of the goalkeeper’s head.

The Saints woke up after that fifth minute let-off as Brooks’s volley into the ground flew just over before Armstrong and Adams tried their luck.

Martin’s men would level in the 18th minute as Brooks slipped in Armstrong to prod through John Ruddy’s legs, with the home faithful’s appeals for offside falling on deaf ears.

The equaliser gave Southampton a pep in its step and Adams saw an audacious long-range effort take a touch off Sanderson and hit a post.

Birmingham was hanging on for dear life, only to go back ahead in the 41st minute. Jan Bednarek managed to flick on rather than clear Sanderson’s hopeful long ball, putting Stansfield behind to blast past Bazunu.

Armstrong saw a curling effort hit the bar and Will Smallbone fizzed across the face of goal as the Saints pushed to reach parity before half-time.

Birmingham began the second half well as Taylor Harwood-Bellis escaped a penalty shout for handball before a Bacuna strike whistled just wide from 20 yards.

Again, the Saints’ sloppiness at the start of a half sparked a vast improvement and they equalised in the 55th minute.

Brooks cut in from the right flank and was left inexplicably open to get hit stunning curling effort past Ruddy.

Southampton scented blood and took the lead four minutes later as Adams controlled a deep cross and showed patience before lasering a shot home.

Birmingham fans’ frustration was quickly compounded by a straight card to Sanderson in the 62nd minute after leaving Smallbone in a heap.

The hosts’ complaints about the decision fell on deaf ears and the Saints tried and failed to put the game to bed.

Instead, lively Stansfield saw a strike come back off a post and Bacuna reacted quickest to fire Birmingham level.

Adams hit a snapshot into the side netting as the Saints pushed for a winner, which finally came during nine minutes of stoppage-time.

Harwood-Bellis headed on a corner and Aribo showed strength and skill to steer home in front of the elated away end.