Chelsea target Lucas Digne has begun talks with Steven Gerrard's Aston Villa in the last few days.
The Everton left-back has interest from the two Premier League sides, along with Newcastle United who are outsiders in the race for his signature.
Chelsea's inaction on signing Digne after his public spat with Toffees manager Rafael Benitez is because their main priority remains to recall Emerson from his loan at Lyon.
What's the problem with Emerson?
The terms of Chelsea's loan arrangement with the Ligue 1 giants prohibit a recall due to the presence of an option to buy in the contract.
The French side are unlikely to activate the option unless they finish in the top three and qualify for the Champions League next season, but are protected by their contract.
They ideally want to keep Emerson due to him being one of the club's best players this season.
However, Thomas Tuchel clearly wants Emerson more than Digne after losing Ben Chilwell to a cruciate ligament injury in November.
Equally, Emerson is understood to be open to returning to Stamford Bridge where he feels he will get another chance to impress the Blues boss.
To break the agreement, Chelsea will have to pay compensation.
Chelsea transfer update
The Blues will also decide on signing a new right wing back by the beginning of next week.
They have so far prioritisied signing a left wing back, but it led them to lose out on transfer target Kieran Trippier who joined Newcastle from Atletico Madrid last week.
They can bring back Blackpool loanee Dujon Sterling up until January 14, but are currently testing the market to see what else is possible.
Furthermore, Malang Sarr is temporarily shunning loan interest following a prolonged run in the first team, while Lewis Baker has had an offer from a Ligue 1 club but has rejected it in favour of remaining in English football.
The homegrown star, who made his first appearance for Chelsea in eight years at the weekend against Chesterfield in the FA Cup, is happy to wait until his contract expires in west London.
Having played in the Netherlands, Turkey and Germany on loan, he hopes for a long-term contract in the English game next season at an upwardly mobile Championship club.
Jake Clarke-Salter has extended his loan at Coventry City until the end of the season despite permanent transfer offers from Belgium and Holland.
Baba Rahman is set to continue on loan at Championship side Reading until the end of the season, even after an inquiry by an unnamed Premier League club during the winter transfer window.
The Blues may also be set to lose their Under-18s captain Josh Tobin, whose deal expires at the end of the season. He has had a few trials away from Cobham ahead of a potential change of club.
Chelsea will wait to do any major business next summer, with midfielders Declan Rice and Aurelien Tchouameni on their shortlist, along with defenders Wesley Fofana and Jules Kounde.
The deals of Antonio Rudiger, Andreas Christensen and Cesar Azpilicueta all expire in the summer, which has only added to the importance of signing a centre-back in the near future.