ALBION'S six-game unbeaten league run ended in disappointing fashion as they finished on the wrong side of a five-goal thriller at St Mary's.
Rudi Skacel's sublime 23rd-minute strike doubled the Saints' lead after ex-Blues striker Stern John had netted a 17th-minute opener with his first goal for the South Coast club.
Tony Mowbray's men, playing their seventh game in 21 days, looked jaded but still created chances in a real end-to-end encounter.
And the ever-impressive Robert Koren took his tally to four goals in five games with strikes in the 33rd and 62nd minutes to claw the visitors level.
However, Albion's parity lasted less than two minutes as John scrambled home his second of the game from a corner to grab what proved to be the winner.
Chris Brunt and Zoltan Gera were restored to the Baggies boss' starting XI as he adopted the same line-up which beat Scunthorpe 3-2 in their last away game.
James Morrison and Craig Beattie were the men to make way as they dropped to the bench.
The first testing shot of the game came in the seventh minute when Inigo Idiakez flashed a low 25-yard drive just past the left-hand post.
The Saints' early pressure paid off in the 17th minute when Idiakez chipped the ball forward to John, who was deemed to be onside, and the ex-Sunderland ace coolly volleyed the ball home from ten yards.
Six minutes later, the Baggies failed to clear from the edge of their area and the ball broke to Skacel who, on his return from injury, hit a sweet left-footed drive across the despairing dive of Dean Kiely and just inside the right-hand upright to double the hosts' lead.
Moments later, Marek Saganowski slotted Idiakez through in the penalty box but he screwed his shot across goal when he should at least have hit the target.
Idiakez came within inches of adding to the Saints' lead on the half-hour mark when he curled a delicious 25-yard free-kick over.
The visitors gradually gained a foothold in the game and created their first real opening when Koren fed the ball to Filipe Teixeira just inside the area.
The Portuguese playmaker turned Christian Dailly with a deft piece of skill but could not beat Kelvin Davis with his cross-shot.
Albion gave themselves a lifeline in the 33rd minute when Brunt swung in a left-wing cross, which Ishmael Miller and Dailly challenged for.
The ball broke free inside the six-yard box and Koren was quickest to react to fire into the net.
Gera then ran onto Brunt's glorious crossfield pass in the 39th minute and pulled the ball back for Carl Hoefkens who, rather than shoot himself, tried to find Miller and lost possession.
The visitors were breathing a sigh of relief four minutes before the break when Jonathan Greening failed to block Nathan Dyer's run, allowing the pint-sized winger to curl a 20-yard shot off the crossbar.
At the other end, skipper Greening's free-kick fell to an unmarked Leon Barnett at the back post in the final minute of the half.
But the giant centre-half could not repeat his goalscoring heroics in Wednesday's 1-1 draw with Stoke and volleyed well over from 12 yards.
Mowbray made a change at the break as Teixeira was replaced by Sherjill MacDonald, who kicked-off on the left wing, with Brunt moving inside in a five-man midfield.
But it was George Burley's men who threatened first as Saganowski fored Kiely into a diving save from Phil Ifil's deep free-kick in the 46th minute.
Two minutes later, Jhon Viafara crossed from the right and Saganowski swooped in to head goalwards. Kiely palmed the ball away before gathering at the second attempt.
Moments later, Ifil knocked the ball into the penalty area and Saganowski spun Barnett and flashed a cross-shot just past the left-hand post.
The tricky Dyer ran at Hoefkens in the 51st minute and curled a 20-yard shot inches wide of the right-hand upright, although Kiely appeared to have it covered.
The Baggies finally got going again when Greening squeezed the ball through to Miller in the box and the powerhouse striker forced Davis to beat out a firm 12-yard strike.
From the resultant Greening corner, Barnett was gifted a free header but nodded well over.
Koren pounced on a misplaced pass in midfield in the 57th minute and fed Miller, who held off Dailly but fired wide from a tight angle as Davis closed him down.
Barnett almost shot himself in the foot a minute later when he gifted possession to the threatening Saganowski on the edge of the box.
Fortunately, Albion's £2.5million summer signing was able to recover to block his shot.
Just past the hour mark, Hoefkens played a sublime pass to MacDonald out on the left wing who pulled the ball back for Paul Robinson.
The advancing left-back let fly from 20 yards and saw his rising drive drift inches wide of the right-hand post.
It was only a temporary reprieve for the Saints.
In the 62nd minute, Miller headed a loose ball forward and Koren held off Wayne Thomas before poking home under Davis to equalise.
But Albion remained on level terms for less than two minutes.
Idiakez drove in a left-wing corner from which John prodded home following a near-post scramble.
Saganowski should have added a fourth in the 67th minute but headed wide from Ifil's cross.
A minute later, Gera picked up a mishit clearance on the edge of the box, only to curl his shot high and wide.
Mowbray made further changes in the 75th minute as Craig Beattie and James Morrison replaced Gera and Brunt respectively.
But it was Saints who threatened next.
Dyer's pace again wreaked havoc before whipping the ball across the face of goal and just past the far post.
An immaculate crossfield ball from Morrison found MacDonald two minutes from time.
The Dutch Under-21 star left Ifil for dead on the left by-line before firing the ball into the six-yard box, where Dailly was on hand to prevent Koren making it a hat-trick.
Miller appeared to be pushed to the ground as MacDonald sent in his cross and referee Pat Miller waved away further Baggies penalty appeals when Beattie went down under Skacel's challenge.
As the Baggies pressed for the equaliser, the hosts looked dangerous on the break and when substitute Andrew Surman crossed Viafara was unlucky to see his goalbound effort ricochet off Albrechtsen and Barnett to safety.
SOUTHAMPTON (4-4-2): Davis; Ifil, Thomas, Dailly, Skacel; Viafara, Idiakez (Surman 83), Safri, Dyer; Saganowski (Euell 90+1), John. Subs not used: Bialkowski (gk), Ostlund, Hammill.
ALBION (4-4-1-1): Kiely; Hoefkens, Barnett, Albrechtsen, Robinson; Gera (Beattie 75), Koren, Greening, Brunt (Morrison 75); Teixeira (MacDonald HT); Miller. Subs not used: Daniels (gk), Pele.
GOALS: SOUTHAMPTON - John (17 & 64), Skacel (23). ALBION - Koren (33 & 62).
BOOKINGS: SOUTHAMPTON - Dyer (foul 90+5). ALBION - Greening (unsporting behaviour 69), Robinson (foul 82).
REFEREE: P Miller (Bedfordshire).
ATTENDANCE: 21,967.
ALBION STARMAN: Robert Koren.
PIC: HOT STREAK...Koren celebrates his first at St Mary's
