The 27-year-old comes up against his former club for the first time as Chelsea travel to St James' Park but Azpilicueta believes that Ba will be more focused on the match rather than the reaction from the home supporters.
Azpilicueta told reporters: "I don't know how [the Newcastle fans] feel. Demba is a Chelsea player. He's going to do his best for Chelsea.
"It's true that he played very well there so I think they must be disappointed because he's a very good player, but he's going to be focused on the game."
Ba has scored three goals for Chelsea in his opening month at Stamford Bridge.