RYAN Bertrand insists playing in central defence comes “naturally” to him as Claude Puel prepares to turn to the left-back amid a crisis at the heart of Saints’ backline.

Saints are desperately short on quality centre-back options and, as a result, Puel has considered shuffling Bertrand into the middle ahead of facing Sunderland's prolific striker Jermain Defoe at the Stadium of Light on Saturday.

Bertrand is usually one of Saints’ best attacking outlets on the left side.

But the England international is willing to swap his swashbuckling role on the flank for a more “high risk” job at centre-back to help shore up the leaky defence, which has conceded ten goals in three games in all competitions.

Despite the enormous responsibility that comes with playing at centre-back, Bertrand, who played there under Ronald Koeman last season – although mainly in a back three, is confident that he doesn’t need to do anything specific in training to adjust.

“It just comes naturally,” said the 27-year-old. “It’s the same defensive principles, but there are different requirements of the job.

“There is no more running forwards as much and there’s a bit more discipline. It’s a bit more of a high risk position, but it just comes naturally.”

“It’s nice to play new positions. It’s good to learn and succeeding in a new position is good for your career,” he added. “If I have to play there, then I’ll play there.”

Once a work permit has been granted and formalities are concluded, free agent defender Martin Caceres will sign for Saints to reinforce the wobbly defence.

After captain Virgil van Dijk’s injury and Jose Fonte’s departure to West Ham, Puel has had no choice recently but to turn to the inexperienced youngster Jack Stephens and usual back-up Maya Yoshida in the middle.

The pair performed admirably in the memorable League Cup semi-final second leg victory at Liverpool, but have struggled in defeats to Swansea and West Ham since.

Consequently, Saints have looked to bring in Caceres, while Puel has mooted the possibility of using Bertrand in there too.

If Bertrand is to make the switch at bottom side Sunderland on Saturday, he will have the unenviable task of shackling the Black Cats’ veteran Defoe.

The 34-year-old is the top-flight’s fifth highest scorer with 14 goals this campaign and is in good form, having netted a brace in Sunderland’s surprise 4-0 win at Crystal Palace last time out.

Bertrand believes, despite his age, Defoe is one of the best goal-scorers in the Premier League.

“Class is permanent and he’s arguably one of the best in the league at what he does,” he said.

“He’s come back and he’s playing – with all due respect – in a lesser side, according to the table at least, but still producing the goals.

“He fully deserves everything and deserves more recognition.

“He’s very professional in his approach to football and that’s continued, proving again that age is just a number and, at the end of it, 14 goals in the Premier League is no small feat.”