At the centre of it all is Enzo Fernandez, with Chelsea still waiting for Manchester City to make their formal move.
A potential deal has been mooted at around £120 million and, remarkably, the possibility of City pursuing the Argentina international has been hanging over Chelsea since the end of the World Cup.
The situation is finally about to accelerate, with sources indicating an offer is City's key area of focus at this moment. Fernandez is likely to be a huge deadline-day narrative, and Chelsea have to be prepared.
They are believed to be willing to sell, and Fernandez himself is keen on the move. The obvious question is why City have left it so late — and how Chelsea react to any offer.
Their preferred solution as a replacement is Lamine Camara, and while their proposed move for the Monaco midfielder has hit a slight hold-up, it does remain possible.
At the same time, they continue to keep the door open on Roma's Manu Kone. There is currently no expectation that Chelsea will sign both players, but they have been exploring the two avenues simultaneously as they assess which represents the best deal.
Most sources have regarded Camara as the more suitable option, meaning the outcome could ultimately depend on how the Fernandez situation develops and whether Chelsea can seal a deal quickly.
There is another potential midfield twist, as interest in Malo Gusto exists from at least two Premier League clubs. Gusto has been used in midfield this season, meaning his potential departure could create yet another hole in an area Chelsea are already trying to reshape.
All of this is happening while the club are attempting to move on at least six other players, including the likes of Robert Sanchez, Marc Guiu and Mykhailo Mudryk.
Additionally, Pedro Neto does not want to leave, but even his situation cannot be completely ruled out, as we reported he is being looked at by a handful of sides.
Chelsea are notorious for being active in the transfer market, and the final hours of this summer's window are certainly going to be eventful.