The 27-year-old striker, whose goal earned victory over Manchester United in the FA Cup quarter-final replay, was taken off at half-time during last weekend's 2-1 win over Sunderland with an ankle injury after a first-half challenge by Craig Gardner.
Ba did not take part in full training on Tuesday and is cup-tied for Thursday night's Europa League quarter-final second leg clash with Rubin Kazan in Moscow, having represented Newcastle earlier in the competition, but should be fit to be considered for Wembley.
Interim manager Rafael Benitez said: "Demba Ba did not train today, just as a precaution.
"It's not too serious. He will not go to Moscow. Hopefully he can train here and be okay for the weekend."
Ashley Cole (hamstring) and his fellow England defender Gary Cahill (knee) remain out alongside long-term absentee Oriol Romeu (knee), while Ryan Bertrand (illness) is doubtful.
If Bertrand joins Cole in missing out, Benitez could field Paulo Ferreira or young midfielder Nathan Ake at left-back at the Luzhniki Stadium. Chelsea hold a 3-1 aggregate lead from the first leg.