Northern Ireland squandered a two-goal lead in the space of three minutes but a 2-2 Nations League draw with Luxembourg was still enough for Michael O'Neill's side to earn promotion as winners of Group 3C.
Northern Ireland looked to be in control after Isaac Price fired them ahead in the 19th minute and Conor Bradley doubled the advantage early in the second half, but Seid Korac got Luxembourg back into it in the 72nd minute - and moments later Gerson Rodrigues fired in an equaliser.
It set up a tense finish at the Stade de Luxembourg but Northern Ireland hung on and the point, coupled with a 1-1 draw between Bulgaria and Belarus, saw them top the group by two points.
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Northern Ireland can celebrate promotion to League B but O'Neill will be frustrated to have let slip what looked like a comfortable lead as his side sought their first competitive away win since beating San Marino 2-0 in March last year - his
first game back as manager.
O'Neill made two changes from Friday's 2-0 win over Belarus in Belfast, one enforced, and together they brought the average age down to 22.2 - Northern Ireland's youngest starting XI since World War Two.
Ruairi McConville, who made his debut as a late substitute last week, came in for the suspended Ciaron Brown, and there was a first start for Ethan Galbraith, his fourth cap coming five years after he made his debut in a friendly against
the same opposition.
The Leyton Orient midfielder was part of a bright, composed start from Northern Ireland, who moved the ball well, with Dion Charles almost through on goal but for a late Korac challenge in the ninth minute.
Northern Ireland's midfield pairing of Shea Charles and Ali McCann were again effective in winning back possession and in doing so set up another chance in the 18th minute, but Price could not stretch to meet Galbraith's low cross.
It was almost a repeat a minute later as Northern Ireland got their goal. This time Bradley won possession, Shea Charles swept it forward and, after a neat step over from Dion Charles, Price bent it into the bottom corner of the net with a first-time shot, his fourth goal in his last six and sixth overall for his country.
Five minutes into the second half Northern Ireland were celebrating again, thanks in large part to a howler from goalkeeper Tiago Pereira.
Bradley's header from Price's cross should have been routine for the goalkeeper but Pereira somehow let it squirm past him - giving Bradley the 100th Northern Ireland goal of O'Neill's two spells in charge.
The Liverpool man should have made it 3-0 in the 65th minute from another Price cross but this time he got it badly wrong, slicing a shot wide with the goal gaping in front of him.
That left the door open for Luxembourg and they soon barged through it. Former Norwich winger Daniel Sinani sent in a free-kick from deep and Korac arrived to prod it home, with Pierce Charles beaten for the first time on his fourth
Northern Ireland appearance.
Three minutes later it was level. Northern Ireland could only half-clear a cross and the ball fell for Rodrigues, who made no mistake as he lashed a half-volley into the top corner.
The game opened up further in the final stages but Northern Ireland hung on to secure promotion.
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O'Neill disappointed after letting lead slip
Northern Ireland manager Michael O'Neill:
"I think when you're 2-0 up in any game and you draw you're always disappointed, regardless of the [circumstance]," O'Neill said. "I thought we played very well in the game, we had a lot of control and we really probably should have put the game to bed.
"At 2-0 we had chances and we didn't take them. To be fair to Luxembourg, they hung in, they scored off a set-piece and then got a good goal that we could have defended.
"From our point of view I think that shows the players how quickly a game can turn. At 2-0 I felt we needed to score again, and the game turned off a set-piece and then a great strike from Rodrigues.
"After that we still had chances to win it, so we're a little bit disappointed, but we've come here and played well. I thought some of our attacking play was terrific, we scored two very good goals and a point was enough for us to win the group."
While the result did not ultimately matter in this Nations League campaign, it leaves Northern Ireland still with only one away win - against San Marino in O'Neill's first game back in charge in March 2023 - in the last three years.
Changing that record ahead of next year's World Cup Qualifiers would have been a major bonus but O'Neill insisted he was not too concerned.
"For me it's not an important marker," he said. "That will come. I don't think that's a significant hurdle for us to think about. It's probably a little bit of learning on how to protect a two-goal lead.
"I thought we protected it fine until those moments and both goals come in the space of a couple of minutes. I suppose it just shows you the nature of international football and how it can change quickly."