Centre-back Cathcart suffered a calf injury during the warm-up for last weekend's Lancashire derby defeat to Burnley and missed the 2-2 midweek draw against Nottingham Forest as a result.
Ian Evatt played in his place on both occasions despite nursing a knee injury of his own.
Veteran striker Phillips continues to struggle with a calf strain and remains a major doubt.
Elliot Grandin is pushing for a start after coming off the bench to net the Seasiders' first goal against Forest.
Blackpool are without a win in three league games but will go above 10th-placed Brighton with a victory.
Brighton midfielder Andrea Orlandi is expected to be back in contention.
The set-piece specialist has missed the last two matches, including Tuesday's 1-0 defeat at Championship leaders Leicester, with a troublesome calf injury.
Orlandi's countryman Vicente is still ruled out, as he makes slow progress in his recovery from a thigh tendon injury, but winger Will Buckley returned to the Brighton ranks at the King Power Stadium, after regaining full fitness following a broken foot, and he looks set to keep David Lopez out of the starting line-up.
Dean Hammond is pressing for a start after dropping to the bench against the Foxes.
Boss Gus Poyet has warned his team he will look to the loan market if the Seagulls cannot end their recent goal drought.
The side have now gone five games without a win and have only found the net once during that time, missing a penalty in the defeat to Leicester.