It's a huge opportunity for Rees against a weakish WBA champion. But,weak at 140lbs not at 130lbs, which Rees has campaigned at.
He has nothing to beat M'Baye with, no size, speed, weight, power advantages which would make a win for him seem extraordinary.
It's his stage however and being Welsh, I hope he wins.
If he were to win, a big fight with Amir Khan would surely be made within a few months, because Kotelnik would beat him in his first defence.