Sky sources understand that Mauro Zarate has passed a medical ahead of his move to West Ham.
The 27-year-old forward, currently playing for Velez Sarsfield in Argentina, confirmed this week that terms for a three-year contract at the East London club had been agreed.
Zarate finished the 2013/14 season as the Primera Divison's top scorer with 13 goals.
No stranger to the Premier League, Zarate scored four goals in 14 appearances on loan at Birmingham City in 2008 when current West Ham owners David Gold and David Sullivan were in charge there.
Zarate told Sky Sports News earlier this week: "It's a new chance for me.
"West Ham called me. They are a fierce team and now I think I want to play (there)."