Defender Hall sat out of the 4-3 defeat to Charlton on New Year's Day with a hamstring strain and will not have recovered in time for the Etihad Stadium encounter.
Goalkeeper Almunia picked up a slight hamstring strain against the Addicks but managed to complete the match and will be monitored.
Midfielder Abi also faces a race against time having been forced off just after the hour mark on Tuesday with a pelvic problem.
There is positive news for the Hornets in the shape of defender Lloyd Doyley, who is fit again against a calf injury.
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