Zigic has shown the improvement desired in training by boss Lee Clark after being dropped for Saturday's 4-0 defeat to Watford due to his poor workrate and attitude during sessions last week.
King also missed the weekend defeat due to a knee injury but is likely to return to the fold to face a Wednesday side who have only lost two of their last 12 in all competitions.
Blues picked up a couple of bumps and bruises at the weekend, but Clark said: "It's nothing too serious and they'll have recovered in time for Tuesday."
Midfielder Keith Fahey is back in training having been on compassionate leave since mid-November to deal with family circumstances back in his homeland, although he now needs time to regain his match fitness.
In further positive news, Darren Ambrose turned out for Blues' Under-21 side on Monday afternoon having been absent for a similar period with a knee problem.