Ben Chilwell will miss the rest of the season as he requires surgery on a knee injury and Everton defender Lucas Digne is said to be the Blues' first choice replacement with Barcelona's Sergino Dest and Ajax's Nicolas Tagliafico also under consideration.
Marcos Alonso is not impressing, meaning the Premier League side could be forced to splash Roman Abramovich's cash in January.
Journalist Fabrizio Romano suggested Digne is 'prepared to leave Everton' and added that possible deals for Dest and Tagliafico are in the early stages still.
Should Chelsea fail to sign any of the three, they have back up options which involves loan recalls.
Emerson Palmieri and Ian Maatsen are both playing their trade at Ligue 1 outfit Lyon and League One side Coventry City respectively.
A recall may not be simple, though, as both clubs would be reluctant to send their players back having featured so heavily this season.
The Italian has started 14 times for the French side whilst the 19-year-old has started 20 times for the Championship team who are within two points of the final play-off place.