Leeds United proved how quickly a play-off tie can change, and Southampton tried to replicate that with the backing of a vociferous St. Mary’s crowd and Flynn Downes fronting the hosts’ relentless pressure.
West Brom had spent most of the opening exchanges trying to slow the game down but shortly after David Brooks had hit the post, Tom Fellows added a burst of pace and floated in a cross that Alex McCarthy awkwardly tipped behind off the crossbar.
The Saints remained patient despite being unable to make an early breakthrough, with Russell Martin’s side moving the ball around well.
In contrast, West Brom struggled to get any meaningful possession and had sloppy moments on the ball, with a Kyle Bartley block being required to deny Adam Armstrong after Alex Mowatt had been pickpocketed in a dangerous position.
The important thing for Carlos Corberán was the tie remaining level going into HT as Joe Aribo curled his effort comfortably off-target with the half’s final touch.
That changed within four second-half minutes, though, as Grady Diangana’s poor pass was cut out by Will Smallbone who laid the ball off to Brooks and got it back off before firing past Alex Palmer having also opened the scoring during the November H2H.
Taylor Harwood-Bellis made a vital intervention to deny Mowatt moments later to preserve that lead, and the Saints felt they should have had the opportunity to double it from the penalty spot following Cédric Kipré’s challenge on Brooks.
Darnell Furlong then saw his venomous strike denied by a strong McCarthy hand as the visitors tried to get back into the tie.
Armstrong wasn’t to be denied at the other end, collecting the ball from Downes and arrowing a pinpoint strike into the bottom corner.
Southampton then got their penalty following a late Fellows challenge on Ryan Manning, allowing Armstrong to clinically convert his 23rd goal of the season as the Saints reach a play-off final for the first time in their history, going one match at Wembley Stadium away from an immediate Premier League return.
They also leave West Brom to plan for a fourth consecutive campaign in the Championship despite Kipré heading in a late consolation.
Flashscore Man of the Match: Adam Armstrong (Southampton)
