Paris Saint-Germain striker Edinson Cavani is a free agent come summer but clubs are vying for his services this month.
It was understood that a gentleman's agreement was in place between the Uruguayan and Atletico Madrid.
However, other clubs' interest has made the situation more complicated and could spark a bidding war.
Cavani is reported to have handed in a transfer request and is angling to leave Paris in January.
The Blues are reportedly willing to pay a £5m loan fee and have informed the player's representatives that they will cover his wages worth £360,000 per-week.
Although, it's understood that PSG would prefer to sell Cavani outright and are holding out for a fee of around £15m.
It remains to be seen whether Atletico meet PSG's demands and pay the money needed to sign the 32-year-old.
Frank Lampard is very keen to bring in competition for Tammy Abraham and Chelsea have an alternative lined up if their Cavani pursuit fails.
The west London club have reportedly identified CSKA Moscow striker Fyodor Chalov as a reasonably priced alternative.
Chalov, who's scored five goals in 19 league appearances this season, is thought to be available for around £20m.
The Russian international returns to action for CSKA on Friday night after a six-week winter break.
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