Leeds United have been to the other side of the world and back since coming up short in May – to Sydney and Sardinia – but began the new season as though they had never been away. Marcelo Bielsa, perched on his blue bucket, saw his side – notably Pablo Hernández – thoroughly outclass a brittle Bristol City team with ambitions of earning promotion themselves. Just as Leeds threatened to turn a convincing victory into a rout, Lee Johnson’s side rallied and Andreas Weimann pulled a goal back but it was insufficient, with the away fans filing out singing: “We are top of the league.”

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A touch of class and some passive Bristol City defending allowed the evergreen Hernández to send a piercing left-footed drive into the top corner before Patrick Bamford doubled the visitors’ lead, nodding in a deft Hernández cross. Jack Harrison put the gloss on a satisfying start to the new campaign.

Bielsa’s side resumed normal service with the bit clearly between their teeth and the kind of unlimited vim that is synonymous with this suffocating Leeds style. Kalvin Phillips and Adam Forshaw ran the midfield, starving City of possession and, in truth, Leeds mesmerised their hosts. “When he [Hernández] adds these type of skills, he is a big value to the team,” Bielsa said.

A lot has happened at Leeds during the close season – Kemar Roofe was absent here and is set to join Anderlecht in the next 48 hours, following Pontus Jansson and Bailey Peacock-Farrell out of the door as the club seek to comply with financial fair play regulations – but this was the kind of boisterous performance that breeds confidence.

Bielsa handed a competitive debut to Ben White and the on-loan Brighton defender exuded class throughout. The Argentinian, who threw on his summer recruit Hélder Costa late on, is down to bare bones but his band of trusty performers prospered. Asked if he would be happy with the size of his squad if Roofe, as expected, departs for Belgium, he said: “We have to adapt if it happens. I can’t be happy if Roofe leaves. If I tell you this when this striker made 15 goals last season, it would be stupid if I accept this situation [as a good thing].”

Phillips supplied Hernández for the opener; the Spaniard was untroubled by Tomas Kalas, an £8m arrival from Chelsea, and allowed to spin on the edge of the 18-yard box before dispatching a deadly finish beyond Dan Bentley, another debutant, in the City goal. Liam Cooper, the Leeds captain, planted a kiss on Hernández’s forehead in delight.

Hernández was the best player on the pitch, humiliating Callum O’Dowda early in the first half by nutmegging him not once but twice and the former Valencia winger created Leeds’ second, though Phillips and Forshaw started the move on halfway. Hernández skipped beyond a static O’Dowda and teed up Bamford, who glanced in. But Leeds were not finished and Harrison pounced to puncture any early-season home optimism after Mateusz Klich’s initial effort was blocked. By the time Weimann struck 11 minutes before time, it was too late on a chastening afternoon.

It is not all doom and gloom for a City side that finished eighth last season. They plan to reinvest some of the £35m they have pocketed from the sales of Adam Webster and Lloyd Kelly by completing a €8m deal for Han-Noah Massengo, a teenage Monaco midfielder who played in the Champions League last season – but Johnson is clear they need to strengthen before Thursday’s transfer deadline.

“We cannot pin all our hopes on an 18-year-old,” he said. “He’s not the saviour, if you like. They [Leeds] were better than us in their brain, their movement and the way they tidied up. I think it shows we need at least five [new signings] if we want to be serious about taking it to another level. The expectation is that we achieve more than we did last year but you cannot keep pulling rabbits out of the hat. It has to be a case of actually getting better with players that are ready to go.”