Initially slated for last week, the Stadium of Light clash was moved due to police concerns about public safety as Newcastle were drawn at home on the same night.
It means the teams already know Chelsea lie in wait in the quarter-finals - something Saints goalkeeper Davis said "doesn't mean anything" right now.
The Southampton club captain is also unmoved by the fact he will lead the side out at his former team on Wednesday, despite spending a difficult year there before moving to the south coast in 2006.
"It's been such a long time since I was at Sunderland and they've certainly had their ups and downs since I left there, and I have as well," Davis told Saints Player.
"So a lot of water has gone under the bridge since my days there, but you always want to do well - firstly for the team you're playing in and for yourself as well.
"The fact we're at Sunderland has no bearing really on what I want to achieve.
"It wasn't a successful period in my career, but I certainly look back on it as a learning period in my career.
"There are things that I learned while I was there that I use today and obviously make you stronger and give you different experiences.
"It's a fantastic club and a fantastic stadium, and when things are going well there everything goes well - but, likewise, when it's not going so well it can go the other way, and that's a certain situation for them at the moment that affects them.
"They've changed their manager and they're certainly in a difficult period at the moment, but it's of no interest to me as we're just looking to progress into the next round of the cup."
Southampton come into the fourth-round clash sixth in the Barclays Premier League and favourites with the bookmakers to progress.
Manager Mauricio Pochettino is expected to ring the changes at the Stadium of Light, having made 11 alterations for the 2-0 win against Bristol City in the third round.
That side still included five senior internationals and highlights the strength in depth at the Argentinian's disposal.
"We've got a strong squad and an ambitious group of players which the manager and the chairman have put together, and we're all looking to play as many games as we can to progress," Davis said.
"I think there's a genuine desire amongst all the lads to be in the first team and I think, with the results putting us in a different position, we're pushing all the time.
"I speak for myself and the other lads that get their chance in this competition that of course you want to do well and show the manager if any changes are needed then you're ready and you're prepared to wait for your opportunity.
"If you stay professional, then it's an opportunity for everyone who steps out on the pitch on Wednesday to do that."