For Southampton, nights like this against one of European football’s heavyweights will live long in the memory, after coming from behind to beat Internazionale on home turf. Yet it was another grim outing for the Italians, who sit bottom of the group and languish 12th in Serie A.

Six years ago this week Southampton supporters walked to St Mary’s for the visit of Dagenham & Redbridge in League One. In 2010, Inter did the double, lifting the Champions League and winning Serie A under José Mourinho. A Virgil van Dijk equaliser and a Yuto Nagatomo own goal later and those days in the third tier provided some incredible context.

“I think we have dominated all of the game on the pitch, we kept a very good spirit and it was a fantastic game and result,” the Southampton manager, Claude Puel, said. “I’m happy tonight for all of the fans, all of the players because they could see a very good game with good intensity.”

It was a special occasion for Southampton, even if Puel’s team selection, with six changes from the defeat by Chelsea on Sunday, did not reflect it.

A throng of Southampton supporters frantically photographed the empty Inter team coach, parked behind the statue of Ted Bates, with the iconic club crest emblazoned across its body. Inside the ground, Southampton placed red and white striped flags on every home seat for supporters to wave.

They did, though, seize the initiative. Jay Rodriguez headed wide from Dusan Tadic’s cross after 44 seconds before Nathan Redmond and Sam McQueen, the academy graduate who made his full debut at San Siro last month, went close.

Inter, who sacked their coach Frank de Boer on Tuesday after only 85 days in the job, seemed nervous and took time to settle. Stefano Vecchi, the interim manager, was coaching Inter’s Under-19s when he was asked to step into the shoes of the Dutchman.

But Inter opened the scoring against the run of play, with their first shot on target, after soaking up pressure for 33 minutes. Mauro Icardi, the Inter captain, stabbed home after Ivan Perisic’s goalbound effort was blocked by Cuco Martina. The goal curbed Southampton’s enthusiasm but not for long.

Puel’s men squandered the opportunity to go in level at the break, missing a penalty on the verge of half‑time. Pierre-Emile Hojbjerg juggled the ball into the box before Perisic handled, forcing Pawel Gil to point to the spot. The spot-kick was delayed, with Antonio Candreva booked for appearing to elbow McQueen, who charged into the box after taking offence at the Italian’s gamesmanship. “I saw him trying to dig up the penalty spot, I just went to stop him and I felt it was an elbow to the jaw,” McQueen said.

The Southampton manager was not too impressed, either. “I think yes, of course,” said Puel, asked if Candreva should have been sent off. “It was important to look beyond that and to come back in the second half, with character and quality.”

When Tadic stepped up to take the penalty, Samir Handanovic saved. Van Dijk ensured Southampton were eventually rewarded. Hojbjerg’s shot at goal forced a corner kick, and from the resulting set piece, Van Dijk, the stand-in captain, forced Handanovic into a magnificent one-handed save. The giant Dutch defender was not to be denied. When Oriol Romeu’s volley from Redmond’s pass struck the bar, Van Dijk was there to poke home the rebound. St Mary’s erupted.

Puel probably did not think the decibel levels could rise any more. They did four minutes later. When Tadic, rejuvenated under the Saints manager this season, crossed the ball from the left, the Inter defender Yuto Nagatomo froze and turned the ball past his own goalkeeper off his left knee.

Internazionale, not for the first time this season, were left out of sorts. “We were caught out by a few lucky ricochets, with the ball coming off the bar, and we were caught on our heels a bit,” Vecchi said. “I think we need a bit of the rub of the green.”

Tadic left to a standing ovation, after being replaced by Steven Davis. Southampton were almost out of sight, but the substitute Charlie Austin was thwarted in his attempts to round the goalkeeper late on.

It’s safe to say the Saints supporters enjoyed every minute of the four added on here. A rousing rendition of When The Saints Go Marching In, sung loudly and proudly by almost every supporter reverberated around the stadium. The Europa League trophy visited Southampton on Monday and this famous win will rightly have left supporters daring to dream.