The Blues to face further Premier League opposition at Portman Road if successful against Saints in third round replay
Mick McCarthy's side earned another crack at the Premier League Saints, after Darren Ambrose's goal ensured a 1-1 draw on the south coast.
Should the Blues defeat Southampton at Portman Road, then Alan Pardew's Palace side will visit Suffolk in the fourth round.
Town's game against Brighton on January 24th has already been postponed, due to the Seagulls progressing in the cup competition.