Ryan Bertrand will become a permanent Saints signing if Ronald Koeman gets his way.

The Chelsea left back has impressed already after joining the club on loan in the summer.

Saints have the option to make the move permanent and Koeman has admitted that if finances allow he would like to see Bertrand join the club full time.

“If we have the money, yes,” said Koeman.

“If it’s up to me, yes.

“Maybe it’s too early to talk about that, but I am very happy until now with the performance of Ryan.”

Koeman has been delighted with the impact of both of full backs, with Bertrand on the left and Nathaniel Clyne on the right, and believes they could even find themselves playing for England together.

“Of course because Clyne was already selected of England and the other one, Ryan, got the opportunity to play every weekend what he missed in Chelsea because he’s still a young player to develop himself and the best way to develop yourself is playing every weekend,” reflected Koeman.

“I spoke to him about that and both are full backs that I like to have because one is defending but an important thing if you like to dominate and play offensive is you need offensive left and right full backs and I am very happy about that.”

Clyne is widely regarded as hugely unlucky not to have already made his England debut.

Asked what the right back has to do to win his first England cap, Koeman said: “He has to continue playing the way he is doing.

“He can’t do more.

“Always show your qualities and finally you need the call from the coach.”

Whilst so much attention has understandably been paid to the Saints frontline after they hit eight goals against Sunderland, Koeman was keen to praise to his defence who have conceded just five league goals this season.

“Good defence and it’s important for clean sheets but it’s the whole organisation in the team because defending doesn’t start behind, it starts in front,” admitted the Saints boss.

“We like to press our opponents, it’s not possible for the whole game but we have to wait for the good moments in the game.

“All of that makes good organisation.

“In football you have to play when you have the ball but without the ball is even more important.”

Saints have been preparing to solve a tough defensive puzzle when they face Stoke this weekend, and the unique threat of former St Mary’s striker Peter Crouch.

“We did this morning unit training,” reported Koeman.

“We made three groups – midfielder, attackers and defenders and specific training for defenders.

“I was a defender but I was not the best defender. I was a good player to build up and score goals but was not good in defence.

“We do sometimes exercise and defending the crosses because Peter Crouch is a striker of Stoke City and one of his qualities is crosses in the box and we have to defend in a good way and that means training.

“We have time to train in the week because we don’t have games, we don’t have European football.”