Ronaldinho, Jose Mourinho, Thierry Henry and now Ralph Hasenhuttl - the football figures blown away by Portsmouth's Fratton Park atmosphere

But it should come as no surprise to the Pompey faithful that the Southampton boss highlighted the noise created at PO4 for the Carabao Cup clash.

Some of the game’s greats have already pinpointed the volume levels generated by Blues supporters after being involved in fixtures at Fratton Park.

Legendary French striker Thierry Henry, ex-Chelsea and Manchester United manager Jose Mourinho, and World Cup winner Ronaldinho are just a few of the footballing stars to have praised the Pompey faithful prior to Hasenhuttl's ringing endorsement.

When the Blues welcomed Italian giants AC Milan to PO4 for a Europa League fixture back in 2008, the travelling contingent and players alike were blown away by the atmosphere.

Pompey wasted a two-goal lead that evening, drawing 2-2 in the end, yet Brazilian legend Ronaldinho simply described the experience under the lights at Fratton on that occasion as 'one of the best atmospheres in world football'.

The PO4 praise has continued down the years, with Mourinho claiming the atmosphere at Fratton Park was better than Old Trafford during his stint as United boss.

Speaking to Sky Sports back in 2018, he said: 'It's not Portsmouth.

‘I remember Portsmouth - such a small stadium, the atmosphere was absolutely incredible.

'In here, the atmosphere is a bit quiet and there is not very (much enthusiasm). But the players like to play at home.'

Legendary French striker Henry endeared himself to the Fratton faithful by wearing a Pompey shirt following a 5-1 FA Cup quarter-final victory for Arsenal back in 2004.

He netted twice that day to send the Blues crashing out of the competition.

Yet Pompey supporters remained after the full-time whistle to applaud Henry for a masterful showing that day.

That memory is something that remained with the French World Cup winner.

He told The Guardian in 2004: ‘It was amazing when we played at Portsmouth.

'They (the Portsmouth supporters) were singing my name for the last 25 minutes of the game, something I've never had in my whole life, and it was as if we were at Highbury.

‘That's why I love the game in England - the people are so passionate.’

Despite managing Pompey’s arch-rivals Southampton, Hassenhutl was the latest to highlight the atmosphere created at Fratton Park.

He said: 'It’s unbelievable. I must also say they didn’t stop singing after being four down.

'You could feel the tradition that is in this derby.

‘I think I have never had such an atmosphere in a stadium so far and I have seen a lot in my entire footballing career.

‘It was a very special game for me also.

‘I was hoping it is coming in a way that you can also celebrate the football and if you see such a game here then you know why football is so popular in England.'

It’s fine list of praise from some of the greats to have graced the game down the years.

But these leading football figures will surely not be the last to credit the atmosphere created inside Fratton Park.