And so it comes down to 90 minutes in Cardiff.
There is a chance for Martin O'Neill's squad to top their World Cup qualifying group and qualify automatically for Russia next summer.
More realistically, the prospect remains of claiming second spot and another November play-off double- header.
It's simply about getting three points against Wales in Cardiff.
Looking ahead to Monday evening in the Principality, O'Neill told RTÉ Sport: "We now know what we have to do, we have to win a game. The chances are there for us. Serbia lost tonight so in points it's now 18, 17, 16."
The Irish manager also referenced the final group against Italy at Euro 2016. We went to Lille knowing that we had to beat Italy to get through to the last 16," he recalled.
"It's there for us. Let's go for it."
Daryl Murphy's first-half brace was enough for the Irish to claim the points against Moldova at the Aviva Stadium.
O'Neill would have liked a greater goalscoring return on the night, but nevertheless was happy enough with the overall performance.
In summing up, he replied: "We got an early goal that settled us and then followed it up with another great goal from Murphy.
"It would have been nice to have got another goal, to get a third goal. We had a couple of other chances. Shane Long said to me on the way in that 'he can't buy a goal'. We also got to the see young Maguire (Sean) coming on.
"The win was the most important thing. It sets us up nicely for Monday night."
"We know what we have to do - let's go for it" Martin O'Neill looks ahead to the do-or-die clash with Wales pic.twitter.com/DvEPnQXtaQ
— RTÉ Soccer (@RTEsoccer) October 6, 2017
As for Shane Long's frustration at not finding the net after an evening where a missed a few clear-cut chances. the Southampton player, nevertheless, is still very much in the manager's plans to spearhead the attack in Wales.
"Obviously, he's still in my thoughts and very much so," was O'Neill's response.
"He had some really good chances. Naturally, he's disappointed, he is a centre-forward and you thrive on making those chances. I don't think they were half chances, they were excellent chances. Maybe on another day he might have scored.
"Players do take a battering sometimes in that forward position.
"You could say that Daryl Murphy takes a battering. Maybe, he dishes it out occasions. It's part of a centre forwards game.
"It's not only about getting into the penalty area and getting across players, it's also about holding up play. If you are playing in the Premier League, that's what you've go to do."
