The agony was etched across every Wrexham face. Just 13 seconds remained of six added minutes at the end of a pulsating fixture when Jack Stephens broke Welsh hearts with a dramatic winner.

Worse still, Phil Parkinson’s side had actually led on 90 minutes, Josh Windass’ penalty separating two teams who last season had been playing two divisions apart.

But then came the first of two body-blows to illustrate just how ruthless the Championship can be, as Ryan Manning’s curled free-kick to level the scores was followed by Stephens’ late, late decider.

No wonder there were so many crestfallen expressions among the 3,000-strong travelling contingent as referee James Bell blew the final whistle to signal Wrexham’s first game at this level since 1982 had ended in defeat.

What was also evident, however, was an air of defiance. “Wrexham, Wrexham, Wrexham,” chanted the Welsh hordes in unison, the pain of such a gut-wrenching defeat partly eased by how well their team had played against a Southampton side strongly fancied to bounce back into the Premier League at the first attempt.

“A lot to build on,” said Parkinson, who will assess over the weekend the ankle injury that forced Kieffer Moore out early in the second half. “A really strong performance with a lot of new players and a lot playing at this level for the first time. We just needed that second goal.

“When we are able to reflect, it was a really proud day for us as a club. It is important now we keep representing the club like we have these last four years.”

It had all been so different 75 minutes earlier.

With Wrexham’s Championship return half an hour old, there had been an air of impudence as the travelling fans sang, “Are you Chester in disguise?” Whether Southampton have ever previously been compared to a team about to embark on their eighth straight season in National League North, the sixth tier of English football, is unclear. But all the locals could do was suck it up.

To be fair to the noisy visitors from Wales, the swagger in the stands had been matched by the confident manner in which their team had taken to a game that had caused something of a stir on the south coast.

This much had been apparent a couple of hours before kick-off when two portable billboards were parked outside St Mary’s Stadium, their purpose to beam an image of the Hollywood hills, complete with the word ‘Southampton’ spelt out in big white letters.

If those arriving for the Saturday lunchtime kick-off still did not get the message, a parody of the ‘Welcome to Wrexham’ poster that advertises the documentary of the same name, complete with Will Still as ‘The Gaffer’, was interspersed with the Hollywood image. Again, the 11 letters that make up the port city were inserted for ‘comedic’ effect.

As with the familiar opposition chant “Where were you when you were s***?” — unusually, not heard on Saturday — such antics are taken as a back-handed compliment by Wrexham loyalists.

After years of being ignored, suddenly their club matters again. And sure, there were plenty of American voices cheering on the visitors in the Saturday lunchtime kick off, including a Super Bowl-winning coach who had flown in just 24 hours earlier with his family to join the party.

But there was also a sizeable hardcore present who had been there throughout the bleakest of bleak days.

The fight for survival under the ownership of Alex Hamilton, the non-League defeats against tiny teams who, in other circumstances, would not have been on the same pitch and the famous weekend, almost exactly 14 years ago, when fan power saved a proud but badly failing football club.

The story of how supporters banded together to raise £100,000 in 24 hours — one even pledged his wedding fund — to avoid being booted out of the fifth-tier Conference is why any opposition chants about glory-hunting fails to glean the anticipated response.

It’s also why returning to the second tier after 43 years meant so much, even to the more recent additions drawn in by the Welcome to Wrexham documentary, fans whose knowledge of those dark days is second hand.

All this emotion made a throaty rendition of club anthem Wrexham is the Name at kick-off particularly apt. As were the many tributes paid to Joey Jones, Wrexham’s greatest servant who passed away last month at the age of 70, on this historic day for the club.

“It’s surreal to see us back at this level after all these years,” said Michael ‘Scoot’ Hett, the lead singer of the Declan Swans who became a breakout star of the Welcome to Wrexham documentary. “Never in my wildest dreams did I envisage watching Championship football again.”

Super Bowl winning coach Paul McCord, his wife Mindy and son LJ are at the other end of the supporter-scale, having been among those who caught the Wrexham bug through the show. Living on the other side of the Atlantic wasn’t going to prevent them being in the away section.

“We just had to be here,” said McCord, a member of the coaching team who took the Baltimore Ravens to Super Bowl glory in 2001 and fell for Wrexham via the documentary.

“Four years of going to football and four tiers of football. It’s been more magical than Disney. Trust me, I live in Florida.”

For 90 minutes, Wrexham did, indeed, look like making supporters’ dreams come true courtesy of an impressive team display.

They were organised, used the ball well and caused all manner of problems for a Southampton side boasting such quality that Cameron Archer, Ben Brereton Diaz and Ross Stewart — three forwards who would surely walk into most teams at this level — had to be content with places on the bench.

Plenty caught the eye in Wrexham’s change colours of green and yellow, particularly among the debutants with Moore leading the line wonderfully with able support from Windass and Lewis O’Brien bringing plenty of energy to midfield.

Defeat was perhaps most harsh on Conor Coady, who was truly outstanding marshalling a back three which also featured Championship rookies Max Cleworth and Lewis Brunt.

“We know we are here to disrupt and upset a few teams in this division,” said Coady, once of the England national setup. “I felt we did that today, bar maybe 10 minutes at the end of the first half and then the end of the second half. We have shown we can play.”

What defeat did underline is the fine lines that exist in this division. Had Ryan Hardie converted when one-on-one against Gavin Bazunu with just a couple of minutes remaining then, surely, Southampton’s fightback would never have materialised.

As it was, Bazunu’s fingertip save paved the way for that crazy, crazy ending.

Welcome to the Championship, indeed.

(Top photo: Dan Mullan/Getty Images)