Connolly, normally a centre-half, should deputise at right-back with Lee Peltier serving a one-match ban following his red card at Aston Villa last weekend.
Peltier’s natural replacement, Jazz Richards, is still out with a foot injury which has kept him sidelined for two months, but the Wales full-back is expected to be available next week.
Bruno Manga will again be absent from the matchday squad with Bluebirds boss Neil Warnock keen to move on the Gabon defender in the January transfer window.
Brighton boss Chris Hughton must decide whether to keep faith with Anthony Knockaert.
The French winger has been substituted in the last two matches having returned to the team following the death of his father.
There is also a decision to be made on the opposite wing, with Jamie Murphy picked ahead of Jiri Skalak for the 2-1 win over Fulham.
Hughton has no new injury concerns but remains without defender Liam Rosenior and midfielder Beram Kayal (both ankle).