Agent Ferrari says Man Utd, Everton target Witsel capable of Premier League success
Ferrari takes care of Witsel's teammate Elaquim Mangala at Standard and is aware of the midfielder's comments this week about wanting a move.
He told tribalfootball.com: "In my opinion Witsel is a very good quality player - even if I see him more in Italy or Spain than the UK.
"In the Belgium Championship you can find some very good and talented players. But they will always have to prove themselves all over again when they move to another top championship."