Both Hasenhuttl and Werner arrived at newly-promoted Leipzig in the summer of 2016. The Austrian manager had just guided Ingolstadt 04 to an unlikely Bundesliga survival, and one of his first signings was Werner, who joined from relegated Stuttgart for a club-record fee.

‘I talked a lot to Hasenhuttl before moving to Leipzig,’ Werner revealed to us en route to training earlier this week.

‘He’s a very nice guy, very jokey, and from the first time we spoke to each other it was a good relationship.

‘It was the next step for me, a different team with different possibilities. It was important for me when I left my hometown to be with a manager with a good idea of football and a good personality.

‘He taught me a lot about pressing, and switching from defence to offence very fast when we win the ball back,’ added our no.11. ‘That was really interesting and helped me a lot in my game. It gave me space for my movements and my strengths.

‘The first season, everything clicked. When we went out, every team member and I never had a feeling we could lose a game. We would go on to the pitch, and it didn’t matter if it was 2-0 to the others, we believed we could win at the end. It was the mentality we had and it was unbelievable.’

Leipzig finished second behind Bayern Munich, a remarkable feat considering it was their debut season in the German top flight. They were helped on their way by 21 Werner goals.

But it was not all plain sailing for the exciting young forward. Initially he had some doubts about whether he was good enough for Leipzig, and then a furore erupted with the way he won a penalty against Schalke midway through the season. It earned him taunts from opposition supporters up and down the country.

‘Hassenhuttl was always a manager who stood behind his players,’ recalls Werner of those more difficult moments.

‘He was not a guy who looked after himself. He was always there for me when I needed help, or when he was asked about me in front of the media, he always stood by me and gave me support.

‘That was really good for me to have a manager like this, and the sporting director Ralf Rangnick. Both gave me the feeling I was not alone in this situation. It allowed me to concentrate on my game and not worry about other things.’

Rangnick replaced Hassenhuttl after his second season in charge, prompting the latter to take over at Southampton in December 2018, and then Julian Nagelsmann became Werner’s boss ahead of 2019/20.

‘Under Nagelsmann I learned a lot about possession, how you can be involved in a game from deep, and see positions where you can put yourself and score and create chances,’ says Werner.

‘That took my game onto another level.’

Amid interest from around Europe, Werner chose Chelsea as his next destination, and he has settled well at Stamford Bridge. One of a number of new recruits, the 24-year-old believes the team are quickly learning each other’s movements and getting a feeling for a fresh style of play.

They will be sternly tested tomorrow when the Saints arrive in west London. Victorious at the Bridge on Boxing Day last season, they have rightly garnered a reputation as one of the league’s most dangerous sides away from home. Werner is expecting an exciting contest.

‘The style Hassenhuttl wants to play in Southampton is exactly the same style he wanted to play at Leipzig when I was there,’ explains Werner.

‘I nearly know what he wants to do and what his plan is, but he has a really good team. I saw his team in some games, they are very strong and we have to be careful in the game because they are very dangerous.

‘On the other side, they defend high which could give us some chances where we could maybe go for our game because we are a team who always can press high or make fast counter-attacks.

‘I think it will be an open game where we have to defend very well, and when we do this we will have chances to make turnovers and play our game.’

If there is one player you would back to exploit that extra space, it is Werner. If there is one manager you would back to stop Werner, it is Hassenhuttl. A fascinating reunion awaits.