Although Chelsea beat Juventus 4-0 in the Champions League match in midweek, the main left-wing defender Ben Chilwell was out of the line of fire due to injury, and many reports pointed out that Ben Chilwell may injure the ACL, and it is likely that he will be absent for a long time due to injury. While Chelsea still have another world-class left-back, Marcos Alonso, but it seems unlikely that he will have to deal with five fronts alone, and Chelsea will have to make a move in the winter window or now to fill the gap.
Chelsea's first viable option would be to reinvent the team's "golden oil" Azpilicueta, putting him in the position of left-wing defender. In his Chelsea career, Azpilicueta actually played a lot of defensive positions, such as left-back under Mourinho, right-centre-back under Conte, Sarri back at right-back, and under Lampard, he also made cameo appearances as left-wingers. In the left-wing position, Azpilicueta's defensive strength is no problem, but because of the cameo against the foot, its attack will be slightly insufficient. If it is only a short period of time as a substitute, Azpilicueta should be fine, but if they want to play for most of the season, Chelsea may still find another talent to cut.
Chelsea have a number of players out on loan, including full-backs, including Emerson on loan to Lyon and Ian Mattson in The Championship in Coventry. Emerson's ceiling is obvious, and he has not been very solid in the past few years at either left-back or wing-back, so even as a substitute, the Italian international doesn't think the Italy international will be useful.
On the contrary, Ian Mattson has more room to develop, Ian Mattson was promoted by Lampard as early as the 2019-20 season, played his first team in the League Cup, and then borrowed Charlton in League One; this season also played well in The Championship Coventry. Now only 19 years old, he has more room and potential for upward mobility, and if he wants to choose a left-hand "taxi" to take his own use, this Dutch U21 youngster is definitely a viable candidate.
Of course, the January reinforcement is also a feasible solution, but there are not many candidates to choose from at present. The Sun also named chelsea four candidates, including Everton's Lucas Digne, Juventus's Alex Sandro, Milan's Theo Hernandez and Brentford's Rico Henry. Compared with the famous top three, Rico Henry may be a more feasible solution for Chelsea, all because the transfer fee of the first three is really expensive; plus Ben Chilwell is injured rather than leaving, and now he is looking for a substitute rather than a replacement, if Ben Chilwell returns, it will be a big waste for the top three. (Of course, Chelsea can indeed be willful if they have money.)