Cork spent three-and-a-half seasons at St Mary’s and will come up against a few familiar faces on Saturday, with the midfielder appreciating the size of the task awaiting the Swans.
“They seemed to have a slow start to the season but they have picked things up well,” Cork said of Saints to the South Wales Evening Post.
“There's a good squad there and good depth. They have some quality players and I think you can see them coming through now in the second half of the season.”
The Welsh side are unbeaten in four matches but were denied a third win in four matches when they were pegged back by Crystal Palace for a draw last time out.
“It's going to be a tough game for us, although we have done well in the last four or five games,” said Cork.
“For me personally it would be great to get a win against my old club. I have some great friends at Southampton and I had some good times there, but we need the points desperately.”
Swansea manager Francesco Guidolin expects Saints to be a tough opponent for his side and revealed his respect for boss Ronald Koeman.
“I remember him as a player, a very, very important player and now a very, very important manager,” said the Italian.
“It will be difficult. Southampton are good. It will be difficult. But we have the possibility to play well and we have the possibility to win.
Saints are on a five-match unbeaten run - including four wins in that time - and have not conceded a goal in over 450 minutes of Premier League action.
“I am happy at the moment but I would be even happier if we had beaten Crystal Palace,” said Guidolin. “We played very well but we must be more clinical in order to win matches.
“We have to take each game as it comes at the moment and our concentration is on Southampton because that is the priority.”