The realisation that he was going to be substituted at half-time must have been up there among the most unpleasant moments of Robbie Keane’s 142-cap Ireland career.

A half-time substitution is an ignominious thing for any player, let alone a captain, and Keane’s mood won’t have been improved by what Martin O’Neill had to say afterwards. Using the traditional coach’s device whereby the most withering judgments come packed in a compliment sandwich, the manager suggested that Keane’s lethargy in that first half had set the tone for Ireland’s leaden display.

“Robbie has been terrific, but he’s not getting any younger,” O’Neill said. “I didn’t think we had great energy in the first half. He just lacked that little bit of energy. The last thing you want to do is take off your best goalscorer.”

The bane of all sportspeople in their mid-30s is the way that any sub-par display is immediately linked to their advancing age. When journalists and supporters do it, it’s irritating. When your coach does it, you’ve got a problem.

Within 30 seconds of the restart Shane Long had made an impact. His first act was to jump for a long diagonal ball forward from the kick-off, then, when he failed to win possession cleanly, he hustled Georgia's captain Jaba Kankava into giving it away just outside his own box, allowing Ireland to push forward along the right side of the field and set up a crossing opportunity for Seamus Coleman.

Long will never equal Keane’s 67 goals but he gives you speed, energy, urgency, a constant presence in the game. The game isn’t won only in the big moments but the small ones and Long is a player who fights a lot of little battles. Georgia’s defence, largely serene in the first half, looked ragged and flustered at times in the second.

It was a pro-active and effective move by O’Neill that helped to swing the match Ireland’s way. So it was curious to hear the manager later resisting journalists’ efforts to give him credit for the decision.

Asked whether he thought Long's influence had sparked that improved second-half performance, O'Neill instead lavished praise on Jonathan Walters.

"No, I think that Jon Walters was a catalyst for a lot of it. What Jon does – whether he's playing right-hand side which he does for the club as often as he does for us there, or up front, he tends to get hold of the ball, which is very very important.

“I’ve known from my old managers before, you know, a lot of play can start from a top-quality centre forward getting hold of it. And Jon does that. And then he’s not frightened to go into the box and go and mix it. He’s got a lot of courage, and he’s been great for us. Really great. His confidence is up, and obviously he gets plenty of encouragement from us all, but he earns that encouragement.”

Something else O'Neill knows from his old managers is that it sometimes pays to withhold praise. When O'Neill played for Nottingham Forest, he seldom heard praise from Brian Clough. It was annoying, but Clough preferred the angry O'Neill, who played like he had something to prove. Maybe O'Neill prefers the angry Shane Long.

Whatever their respective moods, Walters and Long now look the best available Irish strikers, and if they stay fit it’s hard to see Keane starting another competitive international.

One undoubted positive on the night was the performance of Jeff Hendrick, who provided the decisive breakthrough with that superb dribble past three defenders. It was the second time in this group that Hendrick had come to Ireland's rescue with a moment of quality, after his cushioned volley back across the six-yard box for John O'Shea's equaliser in Gelsenkirchen. Last night's assist was his third in these qualifiers overall – the same total as celebrated names like David Silva or Raheem Sterling.

Ever since Hendrick's first appearance for Ireland as a substitute against Poland in 2013, when he set up a goal for Wes Hoolahan with a perceptive pass, he's been giving us signs that he can grow into a player of real vision and insight. Hendrick is repaying O'Neill's trust, and we can hope some of the 23-year-old's creativity might rub off on James McCarthy, who is struggling to rise above a sort of subdued competence.

Ireland are still capable of playing long spells of confused and directionless football, but there is at least a fibrous toughness about this side, a sense that they are becoming increasingly hard to beat. Hopefully that impression will survive the encounter with Germany next month.

The Germany match is a strange one in that only a win for Ireland dramatically alters the qualification picture. As the group stands, there is little practical difference between a draw and a defeat.

Assuming Ireland do not beat Germany, then if Scotland fail to beat Poland at home, a draw between Poland and Ireland in Warsaw will send Poland to the Euros and Ireland to the play-offs. If Scotland do beat Poland, Ireland can qualify automatically by winning in Warsaw. The second of these in particular is a long shot, but all in all, things look a lot better than they did this time last week.