Blues manager Jose Mourinho is eager to add to his attack in the upcoming window with striking trio Fernando Torres, Samuel Eto'o and Demba Ba failing to hit the back of the net on a regular basis.

Mourinho is still interested in bringing Monaco striker Radamel Falcao to Stamford Bridge, but a transfer for the Colombian star is becoming increasingly unlikely due to the French club's huge £80m asking price.

Costa, who was subject of a £20m bid from Liverpool during the summer, is considered by Chelsea as a less expensive alternative to Falcao and has impressed Mourinho with a number of commanding performances in the Champions League for Atletico.