"We can't have any more confidence having come back from Highbury with a 4-2 win," O'Shea told Manchester United Radio.
"I can't say all the words the boss used at half-time, but he certainly got us going. He said that we couldn't let ourselves down like we had done in the first half, that we were too good not to prove it. We got a kick up the backside, but our second half performance showed that we can beat one of the best sides in Europe."
O'Shea's confidence is sky high after netting twice in as many games:
"I've hit a rich vein of form my goal against Middlesbrough gave me confidence when I had that chance at Highbury, without a doubt. Had my confidence been low, I might have turned and played the ball to somebody else. But I got the chance and took it. It was a great way to finish off a really good performance from the lads. If nothing else, it gave us a much easier five minutes of injury time."
"To go to Highbury where Arsenal haven't lost a game in 32 matches and to score four goals was a fantastic achievement. We didn't really want the game to end. It was that sort of game."
And, maybe with an eye for Chelsea's game against the bitters this weekend:
"Chelsea might drop points when we least expect it. That's what happens in football, that is the uncertainty of the game. It throws up results that you don't expect. We're just hoping that the slip-up happens sooner rather than later."
City have been the only team to defeat Chelsea this season so if Chelsea do go on to win the title prepare yourself for bitters claiming to be champions too!!