Mexico midfielder Edson Alvarez will have a medical today ahead of becoming West Ham's first signing of the summer.
Alvarez has been the subject of interest from the Hammers for some time and an agreement has been reached with Ajax over a deal thought to be worth around £35m.
A central figure in the Mexico side that won the CONCACAF Gold Cup in the United States this summer, the 25-year-old is viewed as a replacement for Declan Rice, although his attributes are mainly as a defensive midfielder.
Providing there are no issues, formal confirmation of the transfer is expected on Wednesday.
Alvarez has just returned to Ajax for the start of pre-season training.
The news of Alvarez's impending arrival will come as a relief to Hammers manager David Moyes, who has struggled to bring in reinforcements this summer since Rice's transfer to Arsenal.
West Ham have also made bids for Manchester United pair Harry Maguire and Scott McTominay, although there is no guarantee they will be able to conclude a deal for either player.