Chelsea are continuing talks with Benfica about signing Argentina midfielder Enzo Fernandez.
The 21-year-old World Cup winner has a release clause of about £106m, having joined the Portuguese club in August.
If Chelsea agreed to that amount it would eclipse the existing record fee of £98m paid for Romelu Lukaku and add to the record total of about £270m spent by the new ownership last summer.
Discussions are ongoing about the size of the fee and structure of the deal.
Chelsea's interest in Fernandez continues a recent policy of buying young players with the hope their value will be maintained over the course of long contracts.