Chelsea head coach Thomas Tuchel has said that the club are working on 'internal solutions' in order to get by without the injured Ben Chilwell, but could be forced to look for options in the transfer market if his absence is prolonged.
Chilwell partially tore his ACL last month and has been sidelined since, making his return to on-field rehabilitation earlier this week.
But the England international could still require surgery on his knee if his recovery doesn't go according to plan. If that is the route Chilwell chooses to go down, Tuchel admits Chelsea may need to sign cover at left-back, with Marcos Alonso the only other senior option available in that position.
"First, we must be sure what we do with Ben," Tuchel said (via football.london). "Then we decide if we go for internal solutions and if we trust that we can overcome this period.
"Everything depends on Ben Chilwell and how long he is out. Then on the alternatives, [we can think] if there is something to do, if there is a chance to do something.
"But we did not start this process because we want to protect ourselves and not lose focus on the most important things. The most important things right now are Ben and Marcos. From there we go."
Chelsea have been tentatively linked with a move for out-of-favour Everton defender Lucas Digne in recent days. There have also been claims that the Blues could recall 19-year-old Ian Maatsen from his loan spell at Coventry.
While Alonso is the only natural left-back available to Chelsea right now, Tuchel has used central midfielder Saul and winger Callum Hudson-Odoi in that position already this season.