The skipper’s cool finish in the 66th minute of a tight game proved to be enough as Saints edged out a resilient Baggies team, who showed why they have drawn more games than any other side in the league with a competitive performance.
The introduction of Gaston Ramirez as a second half substitute was influential, as the Uruguayan played the key pass that unlocked a resilient visiting team defence.
It was a goalless game at half-time with little action to note, but Saints were largely on top both in terms of possession and chances created. Albion in contrast, were rarely able to test Artur Boruc who returned in the Southampton goal after a spell on the sidelines.
In an otherwise turgid affair, Boruc made a defining save late on when he scrambled Long’s close range effort clear to preserve the three points as Saints recorded a double of league victories over Albion following their opening day success at the Hawthorns.
The victory also secured retribution for Saints, who were beaten twice by the Baggies last season
Mauricio Pochettino named Boruc in goal after the Polish shot stopper returned from the broken hand that had ruled him out since the start of December.
Lallana regained the captain’s armband as he returned to the starting line up along with Jay Rodriguez with both men coming on as subs in the 4-3 win over Burnley in the FA Cup last weekend.
Guly do Prado was also back in the squad and was named on the bench.
Nicolas Anelka and Shane Long got the match underway for the Baggies who were defending the Northam stand for the first half of a game played almost entirely in the shade, despite the bright weather and clear skies overhead.
Saints were quick to settle into a composed style of high tempo football as the hosts attempted to press back their opponents in the opening exchanges of the contest.
Albion in contrast looked a little ragged as a few hurried touches were on display from the players looking to impress incoming Head Coach Pepe Mel, who was sat in the stands, as caretaker boss Keith Downing oversaw things form the touchline opposite Mauricio Pochettino.
Saints made Ben Foster work for the first time on eight minutes when Schneiderlin and Lallana combined to win back possession before the England man turned to strike a rising shot that the Baggies keeper had to get his body behind for the save.
The attacking intent from the hosts was on show again two minutes later when Lallana turned provider for Rickie Lambert to strike an effort narrowly wide of the right post from the left side of the area.
Luke Shaw put in an effective challenge on Morgan Amalfitano to give the visitors their first corner of the afternoon on eleven minutes. The resulting set piece whipped in by Chris Brunt was purposefully headed clear by Jay Rodriguez.
A few minutes later, Steven Davis went for a spectacular strike when the ball sat up for him from a weak clearance by Jonas Olsson, but the Northern Irishman’s volleyed effort flew well wide of the left post.
That effort was copied by Jack Cork on the back of a corner, but it was the same result again from a midfielder, as the former Chelsea man’s strike never looked like troubling Foster.
Saints continued to impose themselves on Albion with Shaw joining the attack to deliver a cross aimed towards Rodriguez which ended with the ball looping up high into the air before Foster could gather and bring the ball under control.
The Baggies posed their only questions from set pieces. Steven Reid flashed a drive over from 30 yards after Anelka had been brought down by Schneiderlin, before Boruc was called upon to punch Chris Brunt’s free-kick from the right clear after Lovren was penalised for a foul on Long.
The Croat was booked for his challenge on Long, with Saints growing frustrated by the slow pace of the visitors.
Lambert was the next to test Foster when the frontman rattled in a low shot from the left side of the area, reminiscent of the way he shaped to shoot for his goal against Burnley a week previously.
Lambert saw two further crossing attempts blocked by the wall of Baggies defenders before he won Saints a corner with a delivery aimed at Steven Davis which was headed behind.
Albion created an inviting opening for themselves in the 42nd minute when Morrison sprinted clear through the centre to collect Long’s pass, but a combination of Fonte and Schneiderlin ensured that the promising counter-attack was thwarted.
Play immediately swung back up to the other end where Davis picked out Lambert with a delicate chip that the frontman smashed on the volley, but went well over the frame of the goal.
Saints continued to struggle with keeping their shots down, with the efforts summed up by the last effort when Clyne found Rodriguez who blazed over from the edge of the area.
HALF-TIME: SOUTHAMPTON 0-0 WEST BROM
Neither team made changes at the break as Saints got the second 45 started, attacking the Chapel stand.
An early move to try and release Schneiderlin was thwarted by Youssouf Mulumbu , though the follow up attack a couple of minutes alter saw the Frenchman loop a header towards goal which Foster plucked out of the air.
On 51 Saints pushed on again in search of an opening goal when Mulumbu’s loose control in the middle of the park saw the ball break for Rodriguez. The clubs top scorer looked likely to add another strike to his collection as he quickly bore down on goal, but in the end, he skewed his shot wide of the right post.
Albion’s frontmen appeared fortunate to escape cautions when first, Anelka clipped Cyne on the right touchline, before Long kicked out at Shaw after losing possession, but neither challenge was punished by Howard Webb.
Long was eventually booked for a lunge on Schneiderlin just inside his own half as Saints continued to push for a way past the physical nature of the visitors’ defending.
A timely block by Gareth McAuley denied Lambert a clear shot on goal when Davis played the striker in on goal from the edge of the area.
With Saints turning the screw, Gaston Ramirez was brought on in place of Cork with 62 minutes played, to try and unlock a resilient Baggies backline in the final half an hour of play.
Ramirez won a free-kick which he dusted himself down to take. The curling effort was well saved by Foster, who got across quickly to his left for the save.
The Uruguayan’s impact was cemented on 66 minutes when Ramirez played the killer pass from the right channel which released Adam LALLANA who rolled a neat finish under Foster to finally break the deadlock.
The captain’s sixth goal of the season lifted the tension around the ground, with Saints having been largely untroubled by their opponents and looking good candidates to keep hold of their advantage.
West Brom’s Jonas Olsson was booked for a foul on Lallana as the skipper tried to launch a quick break into Albion’s half only to be flattened by the central defender who was out of position.
With the visitors looking to get back into the game, they introduced England Under-21 hotshot Saido Berahino for the final 13 minutes, a move which injected some much needed pace into their frontline.
Inside the last ten minutes Zoltan Gera replaced McAuley, with Albion’s team undergoing a dramatic change in tactic in a bid to snare an equaliser.
The pockets of space seemed to open up more however for Saints. Ramirez linked up with Clyne and Lambert before shooting over from the edge of the box.
Some brave defending by Shaw blocked Amalfitano from sneaking in at the far post, as Albion stepped up their efforts late on.
Saints made a change of their own with goalscorer Lallana replaced by James Ward-Prowse for the final six minutes, with the captain’s armband handed over to Lambert in the closing stages.
Amalfitano was substituted off in favour of another frontman, as Matej Vydra entered the action inside the last five minutes to maintain the Baggies attacking threat.
After Morrison had fired wide, Albion saved their best effort for the 89th minute when Long looked favourite to convert a cross from six yards out, but Boruc spread himself to make a fantastic low save that kept the striker at bay.
On the breakaway, Ramirez had a chance to wrap it up when he sprinted through on goal, but the attempted lob was held well by Foster.
Prior to four minutes of stoppage time being allocated, Guly was brought on in place of Rodriguez with Saints weathering a late storm.
A whipped free-kick by Brunt was pushed away by Boruc, and even the late surge forward by Baggies keeper Ben Foster, came to nothing, as Saints held out for their win.
FULL-TIME: SOUTHAMPTON 1-0 WEST BROM
Southampton team: Artur Boruc, Nathaniel Clyne, Jose Fonte, Dejan Lovren, Luke Shaw, Morgan Schneiderlin, Jack Cork (Gaston Ramirez 62), Steven Davis, Adam Lallana (c) (James Ward-Prowse 84), Jay Rodriguez (Guly do Prado 90), Rickie Lambert
Unused substitutes: Kelvin Davis, Maya Yoshida, Jos Hooiveld, Sam Gallagher
Goal: Lallana, 66
West Brom team: Ben Foster, Steven Reid, Jonas Olsson, Gareth McAuley (Zoltan Gera 80), Liam Ridgewell, Youssouf Mulumbu, James Morrison, Morgan Amalfitano (Matej Vydra 86), Chris Brunt (c), Nicolas Anelka (Saido Berahino 77), Shane Long
Unused substitutes: Boaz Myhill, Claudio Yacob, Scott Sinclair, Diego Lugano
Referee: Howard Webb
Attendance: 28,610 (including 1,621 away)