Own goal means a cruel ending to Northern Ireland's fairytale
Wales 1-0 Northern Ireland
In many respects it was fitting that an own goal proved decisive, because this was one of the tougher watches of Euro 2016. Wales did not care and their delight knew no limits when Gareth McAuley stretched out a leg to divert Gareth Bale's cross into his own net.
Wales have added the latest chapter to a historic campaign - their first at the European Championship and their first at a major finals since their appearance at the 1958 World Cup, when they reached the quarter-finals.
They are in another quarter-final now and they will face Belgium or Hungary in Lille on Friday.
It was a turgid and torturous tie, heavy on physicality and sorely lacking in class, particularly in the last third. But Bale, as he has done throughout the campaign, swung it for Wales. He had scored in each of his country's group games, and here he produced the decisive assist. Taking Aaron Ramsey's pass, he whipped in a vicious delivery from the left and McAuley, who was facing his goal and had Hal Robson-Kanu behind him, could do nothing other than apply the fateful touch.
This was a special date for Northern Ireland. On 25 June 1982 they had recorded possibly their finest ever result - victory over Spain at the 1982 World Cup, courtesy of Gerry Armstrong's goal. There would be no repeat for them here. They brought characteristic endeavour but it was not enough. At full time it was Welsh song that filled the air.
It was a pinch-me moment for both nations because they have been through their share of dark days on the football field. But here they were in Paris, at an arena that they had previously associated more readily with grand rugby occasions, seeking to extend remarkable journeys. Only one would do so.
The Parc des Princes was more red than green in the stands and the composition had seemed to reflect the dynamics of the tie. Wales were cast in the role of the better backed and fancied team - because they had the bigger names, including the biggest one of all, and because they had advanced as the winners of their group. Chris Coleman's team were expected to impose themselves in an attacking sense.
Northern Ireland had done so well to escape a group that included Germany, Poland and Ukraine and their togetherness and organisation was pronounced.
They settled the quicker and twice in the first half they worked Wayne Hennessey. Both moves were nicely worked and advertised their confidence, with the first chance being the clearer.
The ball was worked from right to left for Stuart Dallas to unload a left-footed shot that Hennessey tipped behind. Jamie Ward extended the Wales goalkeeper on the second occasion, on 23 minutes, taking Jonny Evans's pass and thumping at goal from outside the area. Hennessey palmed it over the crossbar.
Bale brought the fear factor, and the big-game temperament, which nobody could match. There had been a revealing moment early on when the Wales superstar accepted possession on the right wing and, very quickly, there were a clutch of white shirts around him. No problem. Bale never looked as though he would be knocked off the ball, he spun and he sent a dangerous ball into the area. Aaron Ramsey could not get a touch to it.
Much of this contest was about brawn. There were spells when the quality was low and the English referee, Martin Atkinson, had decisions to make. Ashley Williams cleaned out Ward at the start, having appeared to lead with his arm - there was no yellow card - while Dallas, having earlier fouled Chris Gunter, jumped into a horrible tackle on Bale. He was booked, meaning that he would be banned for the quarter-final. Michael O'Neill's prediction of an "old-fashioned British game" did not look misplaced.
Wales had to fight their nerves and they failed to do very much in the first half, despite Bale's latent menace. Ramsey had the ball in the net in the 20th minute, after Sam Vokes headed down Neil Taylor's cross, but he was correctly flagged for offside.
Both of these teams have shown themselves to be happier when springing forward on the counter or exploiting opportunities from set-pieces; in other words, playing more reactively. Who wanted to make the game? It spoke volumes that the winning of free-kicks close to the penalty areas was a major source of excitement.
Bale won one from Oliver Norwood in the 56th minute and when he stood over it, Northern Irish hearts hammered. The shot was dipping and swerving and Michael McGovern dived to beat the ball clear. It was the Northern Ireland goalkeeper's first save. Moments earlier Vokes had headed badly off target from Ramsey's pinged cross.
Coleman swapped Vokes for Robson-Kanu, and when he sent on Jonny Williams for Joe Ledley it was partly so he could move Ramsey into a deeper midfield position. Coleman needed to get him on the ball.
It was easy to highlight the individual errors, particularly in possession, where the lack of care was startling. Wales were better in the second half, pressing their opponents back and gradually coming to enjoy the territorial advantage. It was Bale, inevitably, who helped to make the difference.