The 24-year-old was once regarded as one of the best young defensive prospects in Europe, but a couple of injury issues limited him to 31 games across all competitions last season.
According to The Athletic, Forest’s deal to bring him to the Premier League is all but done and Diomande is expected to fly to the UK for his medical later today (Saturday August 8).
It’s understood that he will put pen to paper on a five-year deal, keeping him at The City Ground until the summer of 2031.
New Forest boss Oliver Glasner has been a huge admirer of Diomande for years and pushed Crystal Palace to sign the centre back during his time in South London.
Diomande will become Forest’s third signing of the transfer window, joining Gustavo Sa and Xaver Schlager through the door.