Claude Puel has challenged Virgil van Dijk to fulfil his potential and become one of the best defenders in world football.

The Dutch centre half was again immense for Saints as he scored his first goal of the season and captained the team to an historic victory over Inter Milan at St Mary’s on Thursday night.

Upon taking charge of the club Puel says he was instantly impressed by van Dijk, but felt the 25-year-old was only playing at 60-70 per cent of his potential.

However, with a change of system and tactics, Puel thinks van Dijk is upping his game and insists he can become one the very best in the business.

He said: “I think Virgil since the beginning of the season can make progress because sometimes he was not concentrated, and also I think the play is different to the last year.

“Last year he could defend with strong work back on the pitch and for him this year is different because sometimes he has to defend with 50 or 60 meters behind him.

“It is a new thing and that is difficult because it is hard to defend with the feeling to leave the space behind you, but it is important for me to have a high level.

“When you play against a great team with a striker who is very fast it is important to the possibility of the opponent.

“Virgil improves tactical also and in the duel is fantastic.

“For me he has all the qualities to be one of the best defenders in the world. No problem for this.

“Virgil has the answer for this and has to continue his work and his progress.”

He added: “I was lucky because I train many very good players in all the positions, every time international players.

“But I think when I saw Virgil for me he played 60 or 70 per cent of his quality, because he stayed I think with good comfort, without exploring all his qualities.

“I think now it is important he has this ambition to become a great player and one of the best centre backs in the world. At the moment in the Premier League, and for the next the world.

“He has all the qualities, he make progress every game and it is important he continues this work.”

Saints signed van Dijk for what now looks like a bargain £12m from Celtic in 2015 and he has flourished in the Premier League.

Puel has spoken with van Dijk to tell him how good he can be, and believes the player has the mentality to see it through.

“Of course, since the beginning of the season it was a little difficult with him,” explained Puel. “I don’t keep him in comfort with, for example, the new system and the different philosophy. It was different for him.

“For the first time to defend with a large space in his back, and this is a feeling that is difficult and different.

“It was important to take this and the capacity to defend in a duel or one against one with a player. It is very important with the concentration also.

“He has all the possibilities with the technical, with the physical. He is intelligent and a good character. It is all interesting.

“His development is for him. He is ambitious and now it is important he can give a good answer every time with a good regularity without mistake, without a bad game, and play every time at a good level is very important for him and for his future.”