The Belgium international has emerged as one of the top midfielders in Serie A since signing for Giallorossi, initially on loan, in January 2014 and is attracting plenty of interest ahead of the summer transfer window.
This season, the 28-year-old has averaged 1.9 tackles, 1.3 interceptions, 1.2 created chances and 50 accurate passes per match in Serie A, whilst his Champions League displays have also caught the eye.
According to The Guardian, incoming manager Antonio Conte has made signing Nainggolan a top priority for his first transfer window at Stamford Bridge.
But Roma have rejected the Blues’ latest offer for the energetic midfielder, believed to be worth £23million plus performance-related add-ons.
The Italian outfit reportedly value Nainggolan at around £9million more, but would much prefer to keep him at the Stadio Olimpico alongside equally in-demand midfield partner Miralem Pjanic.