Liverpool are expected to announce their first signing under Jurgen Klopp on Monday.
Marko Grujic will become the first new arrival at Anfield under the German manager when he completes his £5.1m move from Red Star Belgrade.
“On 4th January I will become a Liverpool player,” confirmed the 19-year-old in a post on his Facebook account.
However, the Serbia U21 international will be loaned straight back to the SuperLiga leaders for the remainder of the season under terms of the transfer.
Red Star, who have a 25-point title lead and are unbeaten in 22 league matches, confirmed the deal in a statement on their website before Christmas.