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).
Match facts
- Five of the last seven league meetings between these sides has ended level, with Cardiff winning the most recent encounter (4-1 in February 2016), and losing the other.
- Dale Stephens scored both of Brighton's goals across their two encounters with Cardiff last season.
- The Bluebirds have failed to keep a clean sheet in any of their last 11 home league matches (W4 D2 L5).
- Cardiff defender Sean Morrison has scored one and assisted one of the Bluebirds' last four Championship goals.
- Brighton have kept the most clean sheets in the Championship this season (11).
- Glenn Murray has committed the most fouls of any player in the second tier this season (45).