The Hammers have seen a possible move to Manchester City for Lucas Paqueta thrown into doubt amid an investigation into potential breaches of betting rules.
David Moyes’ side are keen to see whether Paqueta’s move might still happen as they plot their other transfer business.
And Genk winger Tresor is a player of big interest to West Ham.
The Hammers are in contact with the 24-year-old’s camp, according to Belgian journalist Sacha Tavolieri, leaving him fully aware that the Premier League side are keen on him.
West Ham are looking to make progress on a swoop for Tresor next week and are expected to establish contact with Genk.
He is a key player at the Belgian side and contributed an astonishing 24 assists in 39 league appearances last term.
The prospect of a move to the Premier League is likely to appeal to the Belgium international, who has two more years left on his Genk deal.
