Chesterfield winger Gboly Ariyibi is having a medical at Nottingham Forest after a deal was agreed, Sky sources understand.
It is understood the 22-year-old has been the subject of interest from a number of Championship clubs.
Sky Sports News HQ understands that Brentford had a number of offers rejected for the USA U23 international last summer.
Ariyibi has made 36 appearances for the struggling League One club already this season, and 95 appearances for Chesterfield overall, scoring five goals.
He signed for Chesterfield as a 19-year-old from Leeds United in 2014, having joined the Yorkshire side as a trainee from Southampton.
Ariyibi was born in Arlington Virginia and has four caps for USA's U23 side.