Inter Milan midfielder Joao Mario is undergoing a medical at West Ham.
The 25-year-old Portugal international, a Euro 2016 winner, is poised to make an initial switch until the end of the season.
Manager David Moyes confirmed: "He is having a medical as we speak. It is a loan. I'll be able to tell you more once it's done."
Joao Mario joined Inter from Sporting Lisbon for £35 million in August 2016 and has made 44 appearances in Serie A, but he is understood to have grown frustrated at a lack of playing time under new manager Luciano Spalletti.
Moyes has been desperate to add to his increasingly threadbare squad, with Manuel Lanzini and Marko Arnautovic the latest players to suffer injuries.
Andy Carroll is out for three months while Michail Antonio and Diafra Sakho remain sidelined.
That leaves Javier Hernandez and Andre Ayew -- both have been linked with moves away from the London Stadium this month -- as Moyes' only senior forwards.
Moyes revealed West Ham have received an offer for Ayew, who is a reported target for his former club Swansea.
However, he said: "There has been an offer but we wouldn't accept the current bid as it is. I have never said we want anyone to go. If someone comes up we will look at it but as far as I am concerned, no one is going."
Moyes was in Spain over the weekend and watched Real Betis lose 5-0 to Barcelona, but he denied he was there to cast his eye over Betis midfielder Fabian Ruiz.