Fiorentina and Serbia defender Nikola Milenkovic is due to have his medical at Nottingham Forest on Wednesday.
The Reds need defensive reinforcements after selling centre-back Moussa Niakhate and Orel Mangala to Lyon for £27m and £20m respectively.
Milenkovic has 56 caps for Serbia and he played in all of their Group C games at Euro 2024, including the 1-0 defeat by England.
The 26-year-old started his career at Partizan and spent two seasons in their first team before joining Fiorentina in 2017.
In his seven-year stint at the Serie A club, Milenkovic has made 264 appearances, scoring 17 goals and providing five assists.