Zlatan Ibrahimovic's late header earned Manchester United a thrilling EFL Cup final victory over Southampton.
The Saints had fought back from 2-0 down to level, but Ibrahimovic's 87th-minute contribution sealed a 3-2 win and the first silverware of his - and Jose Mourinho's - Manchester United careers.
Wembley bore witness to a superb encounter as expectant United faced a Saints side looking to win just the second major trophy in their history, the first having come 41 years ago when the sides met in the FA Cup final.
Manolo Gabbiadini scored either side of half-time - his fourth and fifth goals in just three Southampton games - as Ibrahimovic and Jesse Lingard strikes were cancelled out.
Europa League and FA Cup glory remain further possibilities this term, but Mourinho will know his players need to up their game moving forwards.
After Gabbiadini had seen an opening goal wrongly ruled out for offside, under-performing United showed their ruthless edge as Ibrahimovic fired home a free-kick before Lingard scored on a third straight Wembley appearance.
But it appeared a gut-punch rather than a decisive killer-blow. Gabbiadini gave Southampton hope with a close-range goal in first-half stoppage time, before sending the success-starved fans wild with an outstanding leveller.
Oriol Romeu crashed a header off the post shortly after avoiding a second yellow card, but it was not to be for Southampton.
Ibrahimovic's 26th goal of the season saw Mourinho become the first United manager to win a major trophy in his debut season, and earned the Portuguese a fourth League Cup triumph - a joint record with Brian Clough and Sir Alex Ferguson.
Few would have known United were the side making a record-equalling 49th trip to Wembley as Saints flew out the blocks.
Dusan Tadic and James Ward-Prowse proved a headache for United's rattled backline, with Nathan Redmond ending a mazy run with an attempt that deflected wide for a corner.
That start should have brought with it a goal in the 11th minute. Southampton's success-starved fans erupted as Gabbiadini turned home hard-working Cedric's cross from the right. Inexplicably, though, the assistant raised his flag for offside, despite the Italian being clearly on and Ryan Bertrand not interfering with play.
Saints soon had further reason to feel aggrieved at Stuart Burt's decision.
Romeu was booked for a lunge on Ander Herrera, giving Ibrahimovic a chance from 30 yards. It was an opportunity the in-form veteran took with aplomb, firing home a stunning free-kick and wheeling off towards his fans in celebration.
Saints' wall and goalkeeper Fraser Forster will feel they should have done better with the 19th-minute strike, which Puel's men busily went about cancelling out.
Ward-Prowse and Tadic forced the returning David de Gea into action from the edge of the box in quick succession.
United were not attacking with the same regularity, but unlike Saints made their threat count.
Marcos Rojo was allowed through to lay off to Lingard just inside the box, with Southampton's lack of pressure giving the attacking midfielder time to calmly side-foot past Forster.
But it was not a fatal strike after Saints collected themselves. In first-time stoppage time, Ward-Prowse's fine right-wing cross was met by a smart Gabbiadini touch, turning the ball past De Gea and turning to the assistant celebrating.
Michael Carrick replaced Juan Mata for a second period Southampton started brightly, with Redmond seeing an exquisite volley kept out by De Gea.
There was no let-up from Puel's men. Steven Davis beat Anthony Martial to a header and Gabbiadini swivelled expertly, firing through a crowd into the bottom corner in front of the Saints fans.
It was a moment of utter joy for half of Wembley - and one Ibrahimovic could have soon rendered worthless, only for Forster to recover from his poor clearance to smother.
Herrera claimed compatriot Romeu should have received a second booking after being clattered, but the appeals ere ignored, with the defensive midfielder soon leaping above Paul Pogba to power a header off a post.
United attempted to make the most of that let-off. A superb challenge from Maya Yoshida prevented Lingard from getting a shot away, before the unmarked winger wasted a glorious 76th-minute chance.
Redmond saw an attempt deflect wide as Saints pushed for a winner, although substitute Marcus Rashford came close to grabbing one at the other end by forcing Forster into a near-post stop.
It was a frantic conclusion and, having blocked a Stephens corner at the other end, Ibrahimovic secured the win.
Unmarked from six yards, he powered home Herrera's cross to secure a memorable win and send United fans wild.
Player Ratings
Manchester United
David de Gea: Produced an impressive save from Nathan Redmond's second-half volley, and was not at fault for Southampton's two goals. 7 (out of 10)
Antonio Valencia: A difficult afternoon for the United full-back, particularly as his team came under such pressure throughout the second half. 5
Eric Bailly: United needed him to impose himself and dominate their defence, but despite his potential he struggled to do so. 6
Chris Smalling: Another performance in which the central defender proved himself short of the level needed to truly succeed at United. 6
Marcos Rojo: Struggled against Southampton's attacking threat and pace on the right wing, and also in his duel against Redmond. 6
Ander Herrera: A fine player but he did little to stop Southampton's energetic midfield stretching United in the final third. 5
Paul Pogba: A composed performance from the world's most expensive player. Was largely responsible for dictating the high tempo with which United built their two-goal lead. 7
Juan Mata: His movement and intelligence stretched Southampton's defence and provided options for his team-mates. Unfortunate to be substituted at half-time. 7
Jesse Lingard: Proved his worth as a squad player and scored United's second goal, which also happened to be his second in Wembley final appearances for the club. 6
Anthony Martial: Contributed to Lingard's goal, but again did not impose himself as he should have with United's superior possession. 6
Zlatan Ibrahimovic: Scored United's opening goal with his 19th-minute free-kick, and provided the attacking threat which proved wrong those in England who felt he was not a big-game player. His header secured victory against the run of play. 8
Substitutes
Michael Carrick (for Mata, 45mins): Was introduced to give United greater control of the game and to preserve their lead. Southampton instead went level and dominated the second half. 5
Marcus Rashford (for Lingard, 77mins): Unable to influence the game as his manager Jose Mourinho would have hoped. 5
Marouane Fellaini (for Martial, 90mins): Surprisingly United's third substitute over Wayne Rooney, but brought on too late to have any sort of impact. 5
Southampton
Fraser Forster: There was little he could do to prevent United's second goal, but he should have saved Ibrahimovic's free-kick for the crucial first and struggled to command his penalty area. 5
Cedric Soares: Provided a consistent attacking threat on the overlap with his pace, and rarely struggled against Martial. 7
Maya Yoshida: Part of the poor central defensive partnership that contributed much to Southampton's undeserved defeat. 5
Jack Stephens: Like Yoshida, contributed to Ibrahimovic being under so little pressure when he scored United's winning goal. 5
Ryan Bertrand: Promising while attacking, and defended consistently enough that United were often not effective enough out wide. 6
Oriol Romeu: Southampton's defensive midfielder provided much of the platform that gave them such control of the second half, even if he needed to provide more protection to their back four. 7
Steve Davis: Typically energetic and industrious. His movement contributed much in making United look so pedestrian throughout the second half. 7
James Ward-Prowse: The promising midfielder's ball-playing ability and intelligence told as the game progressed, forcing United to defend from such a deep position. 7
Nathan Redmond: Consistently threatened United with his pace, and forced a fine save from De Gea when the score remained 2-2. 7
Dusan Tadic: Far from as decisive as he is capable of being. Perhaps Sofiane Boufal should have started in his place. 6
Manolo Gabbiadini: The striker scored Southampton's first goal with an instinctive finish and their second just after the break but was unfortunate when an earlier effort was wrongly ruled out for offside. 9
Substitutes
Sofiane Boufal (for Tadic, 77mins): A talented and creative player who had too little time in which to influence play. 5
Shane Long (for Gabbiadini, 83mins): Brought on to replace the tiring Gabbiadini, but did not get the goalscoring chance his running sought. 6
Jay Rodriguez (for Davis, 90mins): Introduced with Southampton already 3-2 down and appearing to accept victory was beyond them. 5