By SABC Sport
26th May 2024
Saints had won the previous two Sky Bet Championship meetings with their fellow play-off finalists and Armstrong had been on target on both occasions.
History repeated itself at Wembley, with Armstrong able to find the bottom corner midway through the first half for his 24th goal of the campaign and it proved enough to send Russell Martin's team back into the top flight.
It means Leeds, who went close late on when substitute Dan James hit the crossbar, suffered more play-off pain with this a sixth consecutive time they have failed to go up via that route.
Leeds and Southampton were unchanged after impressive second-leg victories over Norwich and West Brom respectively last week and walked out to a raucous but wet Wembley.
Victory in the fixture â- dubbed the richest match in football â- would be worth an estimated ã140million in revenue according to Deloitte and the scale of the prize on offer usually contributed towards cagey affairs.
Farke's men were quick out the traps and Archie Gray, the youngest Leeds player to appear at Wembley, and Wilfried Gnonto had early shots saved by Alex McCarthy, who had not started a league fixture this season for Saints until last month.
Back came Southampton, with Armstrong unable to pick out Will Smallbone in the area before Smallbone had a curled free-kick parried wide by Illan Meslier.
The sun started to break through soon after and with 24 minutes played, it was Saints who broke the deadlock.
Southampton exploited their numerical advantage in midfield, with Flynn Downes able to find Smallbone, who played in Armstrong and he drilled into the bottom corner.
It was first blood to the team which finished fourth in the regular season, but Martin was forced into a change before half-time when David Brooks could not continue and left the pitch close to tears.
Yellow cards started to become more frequent than chances towards the end of the first period until Saints went close to a second.
The duo for the opener once again combined after Smallbone's neat free-kick found Armstrong, but his low effort was saved by Meslier and Joe Rodon cleared the loose ball.
An action-packed start occurred after the interval, with Ethan Ampadu forced to block a shot from Jack Stephens before Leeds went close to an equaliser.
Rodon bombed forward and exchanged passes with Gnonto before he was tackled and Crysencio Summerville curled past the post.
Leeds' club-record signing Georginio Rutter had largely been anonymous in the opening 45, but his influence started to grow and he won a free-kick on the edge of the area after a foul by Taylor Harwood-Bellis.
Harwood-Bellis made amends when he headed clear Summerville's set-piece.
Farke made his first roll of the dice with 24 minutes of normal time to go when he sent James on for Gnonto.
It was a Saints' substitute who had the next chance and Samuel Edozie arguably should have put the match to bed in the 68th minute but curled over.
The door remained ajar for Leeds and they came within a whisker of an 84th-minute leveller when Rutter set up James, but he smashed a half-volley against the crossbar.
James needed treatment soon after before he picked himself up and let fly again in stoppage-time, but McCarthy saved well to ensure Southampton join Ipswich and Leicester in next season's Premier League.