A move to the Premier League side where he previously spent half-a-season on-loan at first started to gain traction after Sami Omorodion's proposed transfer from Atletico collapsed.
Felix is keen to leave Atletico after falling out with boss Diego Simeone, spending last season at Barcelona, but returning to Madrid for pre-season training where he has even been booed by his own supporters.
Now the Portuguese forward who previously scored four goals in 20 games for Chelsea in the 2022/23 season is angling for a move back to England as the Blues embark on a first Premier League campaign under new manager Enzo Maresca.
The player's agent, Mendes, is currently remaining in the UK as he deals with various clubs attempting to wrangle transfers for a number of top players he represents.
Chelsea are continuing to push for a deal to bring Joao Felix back to Stamford Bridge
Chelsea are holding continued discussions with Mendes while also trying to find an agreement on a suitable fee with Atletico Madrid for the 24-year-old who played a bit-part role in Portugal's recent Euro 2024 journey.
Felix became the fourth-most expensive player in history in July 2019 when Benfica sold him to Atletico for £114m, but are unlikely to recover anywhere close to the huge sum.
United announced the double arrival of both Matthijs de Ligt and Noussair Mazraoui on Tuesday, with manager Erik ten Hag also keen to add a midfielder to his squad, but facing the prospect of needing to sell another star first.
Scott McTominay is one likely candidate to leave Old Trafford as Fulham show interest in bringing the United academy graduate to Craven Cottage.