Chelsea are interested in signing Marc Cucurella after Brighton ended discussions with Manchester City over the sale of the defender.
The Seagulls had already rejected one bid from City and see £50m as the benchmark - the fee they sold defender Ben White to Arsenal for last summer.
Sources say it would take an exceptional offer to consider a sale as they see Cucurella as a better player.
Pep Guardiola's side are now exploring other options as the fee is deemed too high.
Cucurella had been identified by City as a replacement for Oleksandr Zinchenko, who left the club to join Arsenal this summer.