The Blues are having a reshuffle in the goalkeeping department, with both Filip Jorgensen and Gabriel Slonina being told they can depart Stamford Bridge.
Robert Sanchez, meanwhile, is likely to remain in Xabi Alonso's plans and will receive support from the returning Mike Penders, who impressed on loan at Strasbourg.
According to the Daily Mirror, Chelsea are looking to add to their goalkeeping union with the addition of Porto shot-stopper Diogo Costa.
Porto value their captain at around £51 million, and will also review that figure depending on how he performs at the World Cup this summer.
Costa has been among some of Europe's most highly-rated goalkeepers for years, and last season kept 26 clean sheets in 53 matches, while conceding just 13 league goals in 31 games.
The 26-year-old would undoubtedly be a huge upgrade on their current options, but it remains to be seen whether Chelsea are willing to pay over £50m for him.