Leeds took the game to Arsenal before holes opened up but they would be a welcome addition to the Premier League

There has been the usual hand-wringing over the FA Cup this week. What is it for? What is its destiny? Do we still need this thing to work the way this thing works?

Well, here was one convincing answer. The point of the FA Cup is to get Marcelo Bielsa’s Leeds United to the Emirates Stadium and then stick them on prime time TV. That ought to do it for now.

Reiss Nelson puts Arsenal through in FA Cup despite Leeds’ best efforts Read more

Arsenal made it to the fourth round of the Cup thanks to Reiss Nelson’s second-half goal. They had the resolve not to wilt in the way so many Arsenal teams might have wilted under this degree of pressure. But the real story was Leeds, who were simply a joy to watch in the first half. Best of all Bielsa’s team were that rare thing in elite sport, a source of constant surprise. Ten minutes before half-time the light blue shirts swarmed through Arsenal’s left side once again and suddenly, outrageously, they were passing the ball around between themselves in the Arsenal box, the home defence overrun, outmanned, bafflingly outnumbered.

Patrick Bamford and Jack Harrison couldn’t quite get a shot away. Somehow the score remained 0-0. But it was thrilling to see a team with the will to flood Arsenal’s backline from the start.

Time and again Leeds’ No10 Ezgjan Alioski seemed to have wandered in from some parallel dimension or abseiled down off the lip of the stadium roof, such were the strange empty spaces he kept finding.

And at times this didn’t look like a standard football match at all. There were too many light blue shirts in among the red ones, too many at the Arsenal end. It looked like a production error, like a Super 8 film clumsily spliced. One kept expecting the picture to jog and the teams to separate, Leeds to retreat to the required respectful distance. Didn’t happen. Kept on going.

This is, of course, how Bielsa teams play. It was a treat in itself to see him on a Premier League touchline, a manager whose influence among the dukes of elite management is so eagerly fanfared it has become a self-fuelling institution in itself.

Bielsa stood and watched the early exchanges, a slightly hangdog figure in club overcoat and glasses: brain whirring, circuits computing the early trajectory of Nicolas Pépé’s slightly madcap dashes down the right.

There was an element of master-and-disciple about a meeting with Mikel Arteta, albeit in a next-gen, one-remove kind of sense. Pep Guardiola’s office wall at Manchester City is festooned with Bielsa quotes, many of which touch on his uniquely high-throttle demands. “Running is understanding, running is everything,” Bielsa has said. For 45 minutes Leeds took this entirely to heart.

Facebook Twitter Pinterest Marcelo Bielsa collects his thoughts. Photograph: Simon Davies/ProSports/REX/Shutterstock

It felt wild, brittle and slightly doomed, as Leeds failed to turn this into goals. But it made for a stunning spectacle, football as a crowd-event, as a shared expression of energy. The boisterous knot of away fans, the intense running patterns, the knot of men in coats on the touchline: there is something collegiate and tightly bonded about Leeds, like watching a brilliantly well-planned travelling stag do unfold before your eyes.

Arsenal started a strong team in the face of this. The only real oddity was the presence of Sokratis Papastathopoulos at right-back, an intriguing take on the notion of the full-back as creative dynamo. Leeds found most of their joy down that side. Three times early on they stormed through on that left flank, Bamford smashing a shot on to the bar with 10 minutes gone.

This was authentic, vibrant Bielsa-ball, the light blue shirts swarming together in small pockets. It is the best thing about his teams when they function as they should, the basic sense of optimism in that running game, every part of the team moving forward behind its most advanced point.

This fearlessness has often ended in success, often in brilliant failure. Here it made for a gripping game of 35 shots , constant sprints and collisions, a rat-a-tat of short, quick passing.

The question as ever is how to sustain that level of intensity, to cover the gaps it will inevitably leave. Leeds needed to score in those moments but couldn’t find the right angle, the right space. Half-time broke their stride. Arsenal finally pulled themselves up to their full height, and 10 minutes into the second half a nice break from Pépé ended with Nelson bundling the ball over the line. From there Arsenal had just about enough to bring Leeds to heel.

It was a beautiful thing to watch all the same, a reminder not just of the quality in English football’s second tier, but of the fine patterns, the basic fun of Bielsa and his running game. Leeds didn’t come here looking for a replay. But they will, with a bit of luck, be back before long.