Ba, 27, also a target for Liverpool and Arsenal, will complete a dream move to Stamford Bridge as the Blues are lined up to activate his £7.5 million buy-out clause. Ba's agent held talks with the European champions on Sunday night but manager Rafa Benitez refused to comment on any developments.
Chelsea have already to sealed the signing of Metalist Kharkiv's midfielder Taison and Corithians' Paulinho. The Brazilian duo are set to join fellow countrymen Ramirez, David Luiz and Oscar.
Meanwhile, Blues may not move for their long-term target Radamel Falcao after he decided to stay with Atletico Madrid until the end of the summer. The £48m-rated Colombia striker was expected to move to London with Chelsea planning to make him one of the highest-paid players in the Premier League.
However, Chelsea are being wise by spending only the required amount after splashing out nearly £100million in the summer.
Chelsea will use the funds raised from the sale of Daniel Sturridge who is on his way to Liverpool. Sturridge, 23, will complete a £12million move to Anfield anytime next week after falling down the pecking order at the Bridge.
Ba, who has scored 13 goals in 20 league appearances, will earn nearly £70,000-a-week and will play upfront to support Fernando Torres
Chelsea fans were delighted to watch Frank Lampard score twice to help them maintain third spot but the veteran England midfielder is not sure about his future at the club.
The 34-year old is set to leave the club in January with clubs from China, the MLS, Paris Saint-Germain and Monaco interested. Chelsea's policy of not offering long-term deals for players above 30 means Ashley Cole, 31, and skiper John Terry, 31, could be heading towards the exit door.
Left-back Cole is already wanted by Real Madrid and PSG while Terry's future is uncertain at the club after numerous controversies and injuries this season.