The Daily Mail says Chelsea have kept a close eye on Neymar for two years and may have to move now to see off interest from Spain.
Both Real Madrid and Barcelona are keen on a player who has been likened to Robinho and, inevitably, Pele - while Manchester City secured first-refusal on him as part of the deal that allowed Robinho to join the club on loan.
If the bid is accepted, City must be offered the chance to match it, and the option of a part-exchange for Robinho is likely to be mooted.
Neymar is 40 per cent owned by an investment group, who must also agree to part with their share to meet Barclays Premier League rules.
The investors pledged earlier this year that they were committed to Neymar seeing out his five-year Santos contract, but after paying just £2m for their share, a quick return of £6.8m could be hard to resist.