Ryan Bertrand is ruled out of Southampton's opening game against Watford through injury

Claude Puel is, however, confident that he has enough cover in academy graduates Matt Targett and Sam McQueen to handle the considerable void that the England international leaves at left back, writes Peter Howard.

The French manager stressed that the problem was not serious, although didn’t put a timeframe on when the 27-year-old would be available again, and added that he wasn’t sweating over the absence of one of his most established stars.

“No, he cannot play the next game, but with Targett and McQueen we have two players that can take his place,” Puel said.

“It’s not important, just something with his knee. He has the same thing as last year. It’s important at the beginning of the season to stay quiet and calm,” he added.

“There’s a lot of games for the future. It’s important to keep Ryan in good form.”

Bertrand, who recently signed a new five-year contract at St Mary’s, has been one of Saints’ standout performers since his switch from Chelsea, initially on loan in 2014, and then permanently in January 2015.

He was then sidelined with a knee injury at the beginning of last season, meaning he didn’t return to playing until late September in the 6-0 thrashing of MK Dons in Capital One Cup, which coincided with an upturn in form for Saints, with the former Aston Villa loanee adding noticeably solidarity at the back.

Bertrand has not made any appearances this pre-season under Puel, and cut a frustrated figure in the stands yesterday as Saints triumphed 1-0 over Athletic Bilbao at St Mary’s in their final preparation match.

The obvious option for Puel would be to select Targett, who played 20 matches last season at left back, although McQueen has risen, somewhat surprisingly, to prominence under the new St Mary’s chief.

“It’s a first time he plays in that position, but I think for the future it’ll be interesting for him to work in that different aspect in defence,” Puel said, who is a big admirer of the 21-year-old.

“He has good running and he can make the difference on the space. For me it’s important that left and right back participate and take the space on the wing.”

Puel’s new diamond 4-4-2 formation relies heavily on the full backs to pound the flanks to provide width in attack, but also tasks them with defensive duties at the back.

Demanding so much of the wide defenders means that Puel sees the need for strong options there.

He said: “It’s important to have two players for the left back and the right back because this position in this [type of] play is very hard,” he said.

“We need players with technical ability – that’s very important for me – and for them to keep running.

“It’s very important because for me they can make the difference and give a good cross or a good passes,” he added.

“It’s important in creation. To repeat the runs is always difficult, but probably with September, October, November, with games every three days, it’s important to count on different players to play in this position.”