Leeds United earned huge praise for their performance against Premier Division big guns Arsenal, but their FA Cup run ended before it began as they went out at the third round stage.
A 55th minute goal from Arsenal youngster Reiss Nelson proved decisive in a classic game of two halves in which the Whites bossed the first period, but found it more difficult after the break.
Some of the football displayed by Leeds in the first half was top class and had their huge travelling contingent singing of their pride in the team, but it will be the Gunners who go to Bournemouth in the fourth round.
"What we needed to do in the match is repeat what we did in the first half," said United head coach Marcelo Bielsa.
"The first half of the team was very, very positive for us.
"We wanted to beat them and after that tried to win the match. The first half was what we wished for. In the second half we understand it is difficult to keep the same control in the match. We should have achieved to try to play a match more balanced.
"In the first half we pressed the opponents' defence more and were able to attack fast. We couldn't do that in the second half."
"For me it would be easy to point at the first half as great and all we wished before the match. Obviously we had 10 chances and we didn’t score.
"In the first half we did three important things, we pressed well their playing out, we made first pass uncomfortable and easy for our defenders to anticipate and this way we avoid the striker to be involved in the play. After you recover the ball quickly in their half we were able to recover fast and combine passes in attack.
"That happened in the first half, but we didn’t do it in the second half. We thought we were in good condition to repeat what we did in the first half, but it wasn’t like that.
"Teams have a process, a development. In some moments, the idealists try to focus on the good things, but in this moment, for our team, even more because we have to play important things. We have to concentrate to have a regular performance, who is playing well."
Bielsa was pleased with the two young players he handed debuts to in an otherwise experienced line-up - Illan Meslier and Robbie Gotts.
He added: "Gotts got what he deserved. The fact he played is up to him because all of it is up to his skill as well. Principally, for his skill and abilities. The person who has to be proud is he about himself.
"He didn’t lose the ball. He defended well. He was close to his man he had to control. When we had the ball he was far from the opponent trying to receive the ball.
"He made few mistakes in the match. He has simple play. He achieved to compete in good competition at this level.
"It was a great performance from Meslier.
"The way he played is very positive for us looking at the future because when the team controlled the match he managed the ball well and when the team was controlled by the opponent he offered good, top level answers.
"The group of the three goalkeepers, Meslier, Kiko and Kamil, plus Marcos Abad (goalkeeper coach), they have made a very good group and work very well together."
Arsenal boss Mikel Arteta said he had warned his players about how good this Leeds team could be.
He said: "(They are) a nightmare for every team to play against. Like going to the dentists.
"A great team. They make it so hard. What they built is powerful.
"It's very uncomfortable for the players when Leeds go man to man. They had to experience that.
“I tried to tell them exactly what they were going to face and after 32 minutes we had won one duel, I think.
"We changed our attitude, desire and organisation at half-time and then we were completely different.
"I watched a lot of Leeds games and they battered every team every three days. It was good for my players to learn and to suffer on the pitch."
A remarkable first half saw Leeds almost completely dominate against one of the big clubs of the Premier with 63 per cent possession and 15 efforts on goal to their hosts' three.
They will have surprised many watching on BBC with the quality of their football, but what will not have surprised the 8,000 Leeds fans in the stadium was that the finishing and final ball was not of the same standard as the approach play. As a result the game remained somehow goalless.
The first hint of a chance came in the third minute when Patrick Bamford sent a flick header wide from a Kalvin Phillips free-kick.
Bamford was played in by Mateusz Klich as United had a three on two, but was too slow, allowing Rob Holding to get back and make a crucial block.
Arsenal's £70m forward Nicolas Pepe got in a shot from outside the box as the hosts put together their first decent attack, but United's debutant teenage goalkeeper Meslier saved comfortably.
It was soon back to Leeds dominance as they constantly took the ball off their opponents in their own half and launched passing moves. One such move ended in a poor header from Bamford from a Jack Harrison cross and another saw Harrison fire in a 20-yard shot that was beaten away by home keeper Emiliano Martinez.
Bamford was unlucky not to open the scoring in the 15th minute with a powerful shot in the area that beat Martinez only to hit the crossbar.
The Arsenal stopper did well two minutes later to keep out another Harrison shot after the winger cut in from the right.
Still it would not go in for Leeds as a Phillips cross-shot from a free-kick was flicked on by Ben White and saved by Martinez.
Next to go close was Ezgjan Alioski with an angled shot that flashed just wide. Alioski then set up Harrison on the edge of the box and his half-volley was saved low down.
A rare Arsenal attack saw David Luiz head wide from a corner before they were soon pegged back again and somehow surviving when Alioski met a superb Luke Ayling cross, but could not get a good contact and Martinez was able to keep the ball out of the net.
Another of Leeds' debutants, Gotts - finally making a start after 35 unused substitute appearances - was in a great position to make a real name for himself, but scooped his shot over from six yards out after being found by Klich.
All the misses and near things came back to haunt United when Arsenal responded to a talking to at the break and came back out clearly more determined to make an impact.
Suddenly it was them doing the pressing and Leeds giving the ball away as the hosts managed three efforts in five minutes, Alexandre Lacazette hitting the crossbar with a free-kick, being denied by Meslier with a low shot from just inside the box and Matteo Guendouzi shooting just wide.
Leeds still carried a threat as a smart break resulted in Bamford's shot from the edge of the box being saved by Martinez when a better option might have been to have played the unmarked Alioski in to his left.
This game could never go on being goalless, but it was Arsenal who struck on 55 minutes when they took advantage of a giant slice of luck as Nelson miskicked his close range shot into the net after Lacazette's pull back had been deflected to him off Barry Douglas.
Gotts hit a shot well over as United looked to respond, but their attacks were far more sporadic now and their opponents could have scored again when Mesut Ozil had a shot blocked and Gabriel Martinelli saw his effort saved by Meslier.
Arsenal were helped by keeping 11 players on the field as referee Anthony Taylor failed to show a single card to Granit Xhaka although he pulled back one player and had a hack at three others during the game in separate "tackles".
When Klich was booked for what looked a bit of retaliation with his first foul on Xhaka he was yellow carded to sum up some of the inconsistency from this official.
He also failed to spot Lacazette kicking out at Gaetano Berardi and although it was more petulant then violent it was similar to Son's recent sending off for Tottenham. VAR was employed, but the home player was allowed to stay on the field - and no foul was given so Arsenal had a corner from which Sokratis had a chance only to head wide.
The Gunners saw out the closing stages well and the only sniff of a late chance for Leeds fell to Harrison, but he was too hesitant after being played in on the left and did not get a shot away.
Leeds United 0
FA Cup, round three
Arsenal: Martinez, Sokratiz, Holding, Luiz, Nelson (Martinelli 67), Guendouzi, Xhaka, Kolasinac, Ozil (Willock 77), Pepe (Saka 90+1), Lacazette.
Leeds: Meslier, Ayling (Stevens 78), White, Berardi, Douglas, Phillips, Harrison, Klich, Gotts (Dallas 60), Alioski (Costa 60), Bamford.
Referee: Anthony Taylor