Chelsea reportedly sent scouts to keep close tabs on AC Milan defender Alessio Romagnoli in Sunday night’s derby.
The 23-year-old passed a late fitness test to start for Serie A giants and impressed for the Italian club despite his team suffering a 1-0 loss to their direct rivals.
According to Calciomercato, the Blues had scouts in attendance to keep close tabs on the central defender as the Premier League heavyweights continue a summer move for the Italy international star.
The 23-year-old star, who has also previously been rumoured with Man United, joined Italian giants from AS Roma in 2015 and has played 120 games in all competitions for the San Siro side.
The Blues reported interest places more uncertainty on the futures of Christensen and Cahill, with the pair currently being heavily linked with moves away from Chelsea.
Meanwhile, Dortmund have reportedly identified three club as future signings.
The German club brought in Sancho from Man City in 2017, and the acquisition of the 18-year-old has so far proven to be a success.
According to The Mirror, Dortmund monitoring the progress in the careers of Callum Hudson-Odoi, Phil Foden and Bobby Duncan.
Both Hudson-Odoi and Foden are highly regarded at Chelsea and Man City respectively, however, neither of the creative duo are featuring regularly for the first team.