However, with Gus Poyet's men sitting bottom of the Premier League table with a game in hand, one point adrift of safety, O'Shea was quick to highlight the importance of replicating the performance today for their remaining four games of the season.
He told BBC Sport: "We can't just do it against the so-called big teams, we have to do it every week and then we'll get a chance.
"We have to believe we can stay up. We've given ourselves a great chance."
West Bromwich Albion, Cardiff and Swansea City travel to the Stadium of the Light before the end of the season, while Poyet's side face Manchester United at Old Trafford in the penultimate gameweek.
The West Londoners had looked to be cruising when Samuel Eto'o fired them into a 12th-minute lead, but Connor Wickham leveled matters for the visitors shortly after.