Cork joined Chelsea as a nine-year-old schoolboy and spent 11 years at Stamford Bridge before quitting to join Saints in the summer of 2011.
He said: “This is a special game for me because Chelsea had such an impact on my life.
“I’m looking forward to playing against them because I never got the opportunity to play with them when I was there. Jose Mourinho was manager when I was there. He was coaching the likes of John Terry, Frank Lampard and Ashley Cole, so to get advice from him was great.
“The main thing that stuck in my head was Didier Drogba pulling me aside and giving me advice on how to defend against players like him. I loved being there but it was said I never got an opportunity. I do feel like I have a point to prove.
“We had a good set of youngsters but the money had just come in, the team had won the Premier League, so we knew it would be hard to get in. I was doing well on my loan spells, coming back and not really making an impression. When I did leave I knew it was the right time.
“I was playing for the reserves in pre-season and I knew it was time to get away. I am not bitter about anything that happened at Chelsea.”