Ireland winger delivered the winning goal
Ireland's James McClean has described the win over Austria as "huge" in terms of its importance in the race to qualify for the 2018 World Cup.
The Derry winger, who had been struggling to get to full fitness after injury in the week leading up to the game, was the hero of the hour in Vienna as his second half goal secured the 1-0 win that sends the Boys in Green top of their group and six points clear of the Austrians, who along with Wales and Serbia, were the sides expected to be in contention for the automatic and playoff qualifying places.
McClean's goal came just after half-time when he was played in on the run by a fantastic Wes Hoolahan through ball.
Without breaking stride, the West Brom player burst into the area down the left channel and showed composure to slot the ball between goalkeeper Ramazan Ozcan's legs and into the back of the net.
Speaking after the game, McClean did not play down the importance of the win in the context of a very even group.
"It's huge. If you look at this group, there's no world class teams, let's be honest," he said.
"But there's four really good teams and Georgia's not a bad side either. We're delighted. It's a massive result."
That winning goal was McClean's third for Ireland in two games after a brace in Moldova proved a crucial haul in the 3-1 away win to put O'Neill's side back in front after being held 1-1.
With three goals in Group D fixtures so far, the ex-Sunderland winger is now the top scorer in the group.
He also now has seven international goals in over 45 games since making his debut in 2012.
Ireland's game kicked off before Wales and Serbia were due to play. Serbia can join the Boys in Green on 10 points at the top of Group D with a victory.