pau Torres,
That's a huge step down.
And that's the problem. Koulibaly has been an established top-tier centre back for half a decade. All of the other players we're linked with are firmly in the "might become world class, might be another Stones" category. And no, I don't count Upamecano as that new contract will make it almost impossible to get him out this summer.
We need someone to come in and be a regular starter at a high standard, we cant afford to give our new CB a season to settle in.