The Reds are reportedly in the market to replace Spaniard full-back Alberto Moreno, and Mariner reckons that Bertrand would be a great option.
"I like him and the way that teams are playing nowadays with the full-backs pushed on, that's exactly what he does," he said on ESPN FC.
"He's decent going forward, he gets crosses into the box, good recovery speed, he can cover the ground.
"Probably, they've always been a selling club. I think Southampton fans will be sorry to see him go but I think there's not many around, put it that way. So I think he goes."