How Pegasus star McCay fired Ireland to historic World Cup win
Ireland's women have now shifted their attention to Thursday's World Cup clash with India following their shock 3-1 win over the United States in Saturday's opener in London.
A draw might be enough for head coach Graham Shaw's side to reach the next phase and fulfil their initial objective of getting out of Pool B by avoiding last place.
India proved they will be tough opposition by holding hosts England to a 1-1 draw in Saturday's other Pool B game.
However, an ecstatic Ireland have made the best possible start and are on course to clinch a play-off for a berth in the last eight by finishing second or third in their group.
The win over the Americans - ranked seventh in the world -was their first since 2015, having lost four and drawn one of the five previous meetings.
UCD striker Deirdre Duke got two of the goals on either side of Shirley McCay's penalty corner effort which made it 2-0 after only 11 minutes.
Margaux Paolino pulled one back from a well-worked penalty corner before Duke got her second in the 40th minute after a counter-attack.
The Irish girls - six are from Ulster - closed the game out expertly as the Americans piled on the pressure in the final quarter, forcing player-of-the-match Ulster's Ayeisha McFerran into several important saves.
Ireland captain Katie Mullan said: "It was an amazing day with the atmosphere in the stadium and all the supporters cheering us on.
"I think we all just really enjoyed it and obviously to get the win was a great start, but a start is all it is."
"We're very aware of that and we now have to focus on India which is the next step towards our goal. It's a massive game for us. We just have to do our preparation, stick to our processes and hope to produce yet another upset.
"But the win over USA has given us a boost. We did a lot of homework going into the game and, as a squad, we knew exactly what we wanted to do.
"We just played our tactics and that was what helped us dominate long phases.
"There were also phases when we had to defend well and Ayeisha was outstanding and fully deserving of the player-of-the-match award.
"But there was no one that didn't have a big impact on the game and that's what we need to build on going forward."
Her Ulster colleague Shirley McCay was delighted with the result and the fact she scored a rare goal in what was her 267th appearance in the green shirt.
"That was only my sixth goal in a long Ireland career and I think set-pieces are going to very important as the tournament progresses," said the Pegasus defender. "It's a great start but we have to have to keep our feet firmly on the ground and concentrate on India now."
Meanwhile, Ireland's Under 18s preserved their top-flight status at the European Championship with a decisive 5-3 win over France in Santander, two of the goals coming from Ulster's Nadia Benallal.
The Under 23s avoided last place at the Six Nations in Antwerp following a 8-7 shoot-out win over Canada.
The Under 16s, though, lost 5-0 to Germany at their Six Nations tournament in Cork to finish bottom.
The boys' Under 18s - just like the girls - also avoided the dreaded drop from European's top flight when they shocked old rivals England 1-0 to make it a three-way tie at the top of the relegation pool. Their superior goal difference did the trick, and so France go down with Poland.
Friends schoolboy Oliver Kidd scored the important goal in what was a superb finish to the competition after a bad start when they lost three games.
The Under 16s lost 3-1 to Germany in the Six Nations tournament in Cork but Wallace High schoolboy Troy Chambers managed to score his sixth goal of the series.
The Under 23s, without four of their star players who are trying to win a place in the senior squad for November's World Cup finals, finished last in their Six Nations series in Antwerp.