West Ham have agreed a £5.5m deal to sign attacking midfielder Edimilson Fernandes from FC Sion, according to Sky sources.
Hammers manager Slaven Bilic last week expressed his desire to sign at least one more midfielder before the close of the summer transfer window, despite having added Havard Nordtveit, Sofiane Feghouli and Gokhan Tore to his midfield ranks.
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Fernandes, who is the cousin of former Manchester City and Leicester midfielder Gelson Fernandes, will undergo a medical on Wednesday ahead of a move to London Stadium.
The 20-year-old came through the youth system at FC Sion and has since made 48 first-team appearances for the Swiss club, scoring two goals.
Meanwhile, Bilic also confirmed West Ham's interest in forwards Wilfried Bony and Simone Zaza on Wednesday ahead of his side's Europa League play-off second leg against Astra Giurgiu.
West Ham are currently without strikers Andre Ayew, Andy Carroll and Diafra Sakho because of injury, leaving Bilic light of recognised frontmen.
Bony has scored just six Premier League goals for Manchester City since joining from Swansea for around £25m in January 2015 and is yet to feature in any matchday squad so far this season under new manager Pep Guardiola.
Zaza, currently of Juventus, scored five times in Serie A last season and also netted the winner in a 3-2 pre-season victory over West Ham earlier this month.