In the seconds after Southampton disposed of Arsenal to tee up an FA Cup semi-final with Manchester City, a camera operator scooted on to the St Mary’s pitch and got to work on locating the match-winner. As the crowd swayed to the sound of Doris Day’s Que Sera, Sera, another lasting image was born.

In between high-fiving and embracing teammates, Shea Charles tilted his head and turned towards the camera, raising his eyebrows a little with a playful ‘how-about-that-then?’ expression. It was a snapshot that snowballed into a viral meme, viewed by millions on social media, and a couple of days later Southampton asked their players to recreate the moment. “I just looked at the camera as if I was looking at my mates down the lens,” Charles says. “I’ve seen it’s gone all over.”

Southampton’s victory had become primetime viewing. This Saturday, 50 years on from winning the Cup under Lawrie McMenemy, the Championship side return to Wembley to face City, whom Charles joined aged seven and left three years ago for Southampton in a £15m deal. He was raised in Flixton, on the outskirts of Manchester, and when he signed to join City’s academy aged eight he was flanked by Patrick Vieira, fresh into a youth development role after his retirement from playing.

There is a brilliant photograph from around that time of Charles and his giddy teammates meeting Vincent Kompany on a tour of City’s training ground. For Charles, who grew up idolising Kompany and often played at centre-back through the age groups, it was a touch surreal. “That was such a mad day for all of us,” says Charles, who is a No 6 these days. “At that age, there were a lot of City fans in the group. All the boys that were signing on for under-nines got a little treat to see some of the players and then we went to the game where City beat United 1-0 [in April 2012], when Kompany scored the header. His kind of era at City was my childhood; him and Yaya Touré were my favourite players. When Kompany was doing his coaching badges, he did a session with us when we were under-14s or under-15s.”

One of Charles’s final acts for City was a captain’s speech in modest surroundings at the County Ground in Leyland, Lancashire, after retaining the Premier League 2 title, a month before Pep Guardiola gave him his Premier League debut at Brentford on the final day. The details from west London remain fresh in his mind. “I came on around the 63rd minute,” he says and the records confirm that, as a replacement for Nathan Aké. “I got told to warm up and I remember making sure it was me that they were talking to. Then he [Guardiola] said: ‘You know how good you are, just go and do what you do in training.’”

Charles first trained with Guardiola’s group when he was 17, when several first-team regulars were absent because of Covid-19 and the postponed Euro 2020 tournament. “When you first go up, as a City fan, I was a bit starstruck: ‘Woah!’ Suddenly I’m training with [Riyad] Mahrez. Fernandinho was there, someone I always tried to ask things. He helped me with little details – positioning, knowing when to drop at the right time. I tried to get bits of information from him. And Rodri as well. I ended up playing against Rodri in a friendly … it’s not fun to play against him, I’ll be honest.”

The game in question was a couple of years ago, a 5-1 defeat after Northern Ireland seized the lead inside two minutes in Mallorca, Spain’s final warm-up game before winning Euro 2024. That day Charles, who impressed in defeat against Italy in the World Cup playoffs last month, was pitted against a midfield of Rodri, Pedri and Fabián Ruiz. Why is Rodri so good? “He makes the right decisions 99% of the time. He moves the ball so quickly, it’s hard to get near him. Especially given the other opposition players around me in that game … it was just tough. I always tried to focus and learn from Rodri at training.”

For Charles, whose first Saints goal came at Anfield in a Carabao Cup defeat last September, his ice-cool finish against Arsenal, controlling the ball on his left foot and finding the corner with his right, represented another clutch moment. There was his 96th-minute winner in February’s extraordinary 4-3 turnaround at Leicester, Saints having trailed 3-0 after an hour; and a goal-of-the-season contender against Oxford last month, a first-time strike into the top corner from 30 yards, the xG 0.011. Last weekend, after entering at half-time against Swansea, he equalised in a game Southampton won to fuel once more unlikely automatic promotion hopes. Saints were 21st when Tonda Eckert took the reins as head coach in November, initially on an interim basis, but are now three points off second-placed Ipswich, whom they host on Tuesday.

Eckert recently acknowledged Charles’s progression from prospect into consistent performer and the 22-year-old believes last season’s loan at Sheffield Wednesday, where he won player of the season and played alongside his younger brother Pierce – a highly regarded 20-year-old goalkeeper – enhanced his development. The pair shared an apartment in the city and their parents, Mary and Kelvin, were regulars at games. “I feel like my time at Wednesday really helped me come into my own, having a lot of responsibility within a team and playing a lot of games. Playing for Northern Ireland also helps me have a leadership role – I’m nowhere near one of the youngest in that group now, which is really weird – so all of that really helped me go into this season.”

Charles’s winner in the previous round was typical of his understated style; as teammates kickstarted the dressing-room celebrations, La Roux blaring over the speakers, he was debriefing the game with Sam Edozie, one of three former City youngsters, together with Taylor Harwood-Bellis, who could face their former club. “My dad’s dead chill, so that’s probably where it stems from,” says Charles, a middle brother, with the eldest, Eoin, a defender for Wythenshawe in the North West Counties Football League. “If we go behind in a game, I like to think that I’m a cool head that people can turn to as a leader. It’s just always been a kind of strength of mine.”

In midweek Southampton made it 20 games unbeaten – Lincoln are the only side in the top four tiers on a longer streak without defeat. Saints have won eight of their past nine but face the ultimate test. “We managed to do it against Arsenal, so we feel like we can do it against anyone,” Charles says. “We know we’re up against probably the best team in the country right now, so it’s another exciting challenge.”