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.
Rafael Benitez: "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."