The Black Cats beat City 1-0 at the Stadium of Light on New Year's Day when substitute Ji Dong-won struck at the death after Martin O'Neill's patched-up side had survived something of a mauling.
The former Manchester United defender, who helped his side to a first league win of the season against Wigan last weekend, said: "It's a totally different situation. City have added to their squad, we have added to our squad and made some changes along the way."
The Black Cats almost repeated the feat at the Etihad Stadium in March when they led 3-1 with just five minutes remaining, only for the home side to snatch a draw with late strikes from Mario Balotelli and Aleksandar Kolarov.
Sunderland were the only side to deny Roberto Mancini's men Barclays Premier League victory on their own pitch as they clinched the title, although O'Shea, who was missing through injury that day, knows recent history will have no bearing at all when they return.
"It's a tough game for us, we are under no illusions. We will have to play very well," added O'Shea.
"But it's one we can go into now with confidence because we got that win against Wigan, and have had all the good performances away from home.
"It's been put to bed, we have got that win on the board and we can move forward now."
Source: PA
Source: PA