A team featuring only two of the men who started Ireland's final game at the Euro 2012 finals last summer - defender O'Shea and midfielder Glenn Whelan - came within seconds of taking a firm grip on second place in Group C last night as they led rivals Austria 2-1 deep into injury time.
However, they woke this morning to see themselves still in fourth, level on points with the Austrians and the Swedes having passed up a major opportunity after David Alaba snatched a draw with a last-gasp equaliser.
Manager Giovanni Trapattoni bemoaned the relative inexperience of his new-look side in the immediate aftermath of the game, and O'Shea agreed.
The 31-year-old said: "It's hugely frustrating, but we need to learn from this experience - the young lads as well - in the last few minutes of games to kill teams off, just kill the game off and keep the ball.
"They [Austria] were very clever and the referee bought a lot of their fouls in the second half, he was giving them a lot of easy decisions.
"They were just jumping and screaming half the time and he gave the free-kicks, which is a little bit frustrating.
"But it's something in international football you have to grow up and learn from quickly."
The draw, which gave Ireland two of a possible six points from their trip to Sweden and the clash with the Austrians in Dublin, was all the more frustrating as they had recovered from a bad start to force their way in front.
O'Shea's central defensive partner Ciaran Clark was punished for dwelling on the ball with just 11 minutes gone when he was robbed by Zlatko Junuzovic, who set up Martin Harnik to score.
However, the Republic were back on level terms within 14 minutes after Jon Walters converted from the penalty spot following Emanuel Pogatetz's trip on Shane Long.
The West Brom frontman was desperately unfortunate not to give his side the lead when he cleverly back-heeled James McClean's shot against the foot of the post, but Walters struck again with a header in first-half injury time.
It was a lead they would defend until the dying moments of the game when, with Trapattoni's men retreating ever deeper, Alaba's shot clipped substitute Sean St Ledger and flew over keeper David Forde and into the net.
O'Shea said: "To get ourselves back into the game so well and to look like we are picking up a massive three points, the frustration is incredible.
"But we gave Austria half a sniff. They were very fortunate with the goal as well - it deflected off one of the lads' legs.
"If we had let the lad shoot, it probably would have gone straight into Fordey's arms."
Ireland return to competitive action in June when they face group minnows the Faroe Islands at the Aviva Stadium, although they will have one eye on Vienna as Austria and Sweden go head-to-head on the same night.
Trapattoni seems likely to still be at the helm - he certainly had no intention of going anywhere last night despite speculation that his reign could be drawing to a close.
But his side now needs to pull off a special result somewhere along the line if they are to resurrect their hopes of claiming a play-off place.
Despite his disappointment, O'Shea, who wore the captain's armband in the absence of the injured Robbie Keane, was bullish about their chances of doing just that.
He said: "The positive you take from it is we have nothing to be fearful of either going to Austria or Sweden coming here.
"We are respectful of them, but we know now, and some of the younger lads will know now, we are more than capable of winning those matches."