Chelsea have reportedly made progress in sending Diego Costa back to Atletico Madrid as the Blues prepare for a busy time in the final days of the summer transfer window.

Antonio Conte had already informed the Brazil-born Spain international, via text message, that he is no longer in his plans at Stamford Bridge, and the striker has not returned to the club since the pre-season as he is looking for a move away from the west London club.

According to The Telegraph, the Premier League winners are edging closer towards agreeing a fee with Atletico for the sale of Costa. The fee is believed to be around £40m ($51.7m), plus significant add-ons.

The Spanish capital club are banned from registering any players signed during this summer transfer window. This situation is likely to force Costa to go out on loan until January or even Atletico putting him under a specialised training regime in case he stays with the La Liga side.

Ronald Koeman's Everton and Ligue 1 clubs AS Monaco and Marseille are interested in taking Costa on loan until January. If Atletico decide to allow Costa to go out on loan, it remains to be seen as to which clubs will be able to secure his services.

Diego Costa
Costa has won two titles with Chelsea Getty Images

Meanwhile, the English champions have reportedly agreed a fee with Arsenal for Alex Oxlade-Chamberlain. The England international has one year left on his contract and has already rejected a final contract offer worth around £180,000-a-week ($230,000 per week) at the Emirates.

The Blues have reportedly agreed a £35m ($45.3m) fee with the Gunners and are now set to discuss personal terms with the player.

However, Chelsea are not the only club interested in signing Oxlade-Chamberlain. Their league rivals Liverpool are also in the race for the former Southampton man's services.

The Stamford Bridge outfit are aware of Liverpool's interest and are hoping that the Merseyside club will not match their bid for the 24-year-old.

Liverpool are looking to sign either Lemar or Oxlade-Chamberlain and will make a firm approach for the latter if Monaco decide against letting the France international leave.

According to reports, Conte is looking to make four new signings before the transfer deadline and the list includes Oxlade-Chamberlain, Leicester City midfielder Danny Drinkwater, Everton's Ross Barkley and Swansea City forward Fernando Llorente.