RALPH Hasenhuttl admits his previous working relationship with Zsolt Low will make tomorrow's contest against Chelsea "very difficult", adding: "He knows our shape very well."

The pair worked together at RB Leipzig for two years between 2016 and 2018, before Low departed to join Thomas Tuchel at PSG and now Chelsea. Hasenhuttl also left Leipzig a few months after Low's exit, to become boss at Saints.

During their first season at Leipzig, Hasenhuttl and Low guided the club to a second-placed finish in Bundesliga.

Discussing the prospect of coming up against Low and Tuchel at St Mary's, Hasenhuttl said: "I don't know only him (Tuchel), I also know his assistant coach very well, Zsolt Low.

"He is fantastic and I worked with him for two years at Leipzig and he was my assistant coach. He knows me very well I think.

"He knows the way we play very well and that doesn't make it easier for us to be honest. But the challenges you have in the Premier League are always not easy.

"Thomas didn’t talk to me (before Low went to PSG), he knew him from before and how good he developed his football knowledge.

“In the second year before the end of the season, I knew that he would leave in the summer to go to Thomas because he wanted to work under a new manager that was a little bit more possession-oriented, to learn new things.

“We had in Leipzig in that moment a very one-dimensional way of playing football or, rather, the guidelines were very one-dimensional.

“That was also the reason why for me it was important to move and to go my own way then and to develop my game in all parts of the game.

“I think it was important for us both to make this step. I think we both now know more about football and we learned a lot in the past few years.

“It will be very difficult for us because he knows our shape very well. He knows everything about it.

“He knows also how tough it can be when you play against us when you do it perfect when we play this shape. It will be interesting."

Tuchel has made a good start to life as Chelsea boss, winning five and drawing one of his six games in charge so far.

Tomorrow is set to be the fifth meeting between Tuchel and Hasenhuttl, with the former currently leading 3-1 in the head-to-head record from his time at Borussia Dortmund.

Asked how much the German has changed Chelsea since arriving, Hasenhuttl said: "It's obvious he knows what he does and is a manager that immediately brings his gameplan into the team. You can see the development of Chelsea in this short time he is that is massive.

"They play a completely different style of football now. This for me is a signal of a manager who has a clear plan."