Harry Kane is Leyton Orient’s most famous loanee, but it was a goal from the boot of another player borrowed from Tottenham Hotspur that will go down in club folklore and gave Manchester City a huge FA Cup scare.

The record books may have Orient’s opener as a Stefan Ortega own goal, but anybody who was at Brisbane Road – including Noel Gallagher – or watching on television will remember it as Jamie Donley’s.

It was a goal any of City’s superstars – and Kane for that matter – would have been proud of as Donley beat Ortega with an incredible 50-yard shot. The ball hit the underside of the bar and rebounded back off the goalkeeper into the net, and it was all down to Donley.

Donley is on loan from Spurs, just as Kane was back in 2011, and whatever the 20-year-old midfielder goes on to achieve, he will never forget his moment of magic against City – even if it was not quite enough to claim a famous win.

“I know I hit the goal well,” said Donley. “I knew it fell for me nicely. I saw him off his line and luckily it went in. It will be a happy moment. It would have been a lot nicer if we won. It was disappointing we lost, but it was a good moment.”

The visitors complained that they should have been awarded a free-kick for a foul by Sonny Perkins on Nico González, making his City debut, which allowed Donley to shoot, but there was no VAR to save them.

González was forced off with an injury suffered in the challenge, but Guardiola felt it was a good introduction to English football for the Spaniard.

“I think he understood perfectly what England is,” said Guardiola. “It’s a pity because I don’t know how hard the kick is, but he could not continue. My first game was against Stoke City. I realised immediately what the Premier League is.”

Other than catching out Ortega, Donley also produced a goal-line clearance from City substitute Bernardo Silva to preserve Orient’s lead until half-time. But the League One team could not quite see out the job, as second-half goals from Rico Lewis and substitute Kevin De Bruyne saved Guardiola’s blushes.

Donley was not the home team’s only hero. Charlie Kelman, who went close to restoring Orient’s lead after Lewis’ lucky leveller, that deflected in off Abdukodir Khusanov, was a constant threat, Diallang Jaiyesimi worked himself into the ground and goalkeeper Josh Keeley, also on loan from Spurs, made a couple of smart saves.

“I’m proud because we created chances, we caused them problems, the atmosphere was brilliant,” said Orient manager Richie Wellens. “At least it took the big boy to come on and beat us. Our chairman’s buzzing [that] he met Pep.”

On Donley, Wellens added: “The lad has talent. Spurs have been great, loaned us one of their best young players and we think we’ve developed him really well over the last six months. And if he carries on, he might be playing against them [City] week in, week out.”

De Bruyne to the rescue

After Lewis had equalised just short of the hour mark, Guardiola, who was serenaded by home chants of “you’re getting sacked in the morning”, had to throw on De Bruyne and Phil Foden to save his team being taken to extra-time.

Kelman almost put Orient back in front from a Donley free-kick before De Bruyne managed to squeeze the ball past Keeley from a tight angle for what proved to be the winner.

Defender Dan Happe missed a wonderful chance to score a dramatic 90th-minute equaliser for Orient, volleying over the crossbar from close range after being left unmarked at the back post, as City just about scraped into the fifth round.

“They had clear chances but we are a small [in height] team and you are going to suffer,” said Guardiola. “The keeper made a fantastic game. When you are 2-1 up in the FA Cup in the last minutes, you are going to suffer because they bring on players and they can do it.

“We were lucky at the end because they had chances, but we created a lot of chances. It was a tight game, we knew it, but we behaved really well, we reacted with character and it’s always nice to be in the next round.”

City can now prepare for the visit of Real Madrid in the Champions League on Tuesday night, when Orient entertain Mansfield as they resume their bid to win promotion to the Championship.

“I know it’s weird, but I’m delighted it didn’t go to extra-time because that would have been a struggle for us,” said Wellens. “Were we going to win the FA Cup? No. Can we win promotion? Absolutely.”

Here is how the moment of Cup magic happened . . .

City midfielder hassled

Orient were clever with their pressing and picked their moments to pressurise City players. It was Nico González, the January signing making his debut, who was targeted. The £50 million recruit was facing his own goal and thought he had time to dither. He did not. Three Orient players converged on the City midfielder, who tried to convince the referee to blow for a foul. When play was waved on Donley knew what he was going to do.

Donley judges it to perfection

With the ball at his feet just inside the City half, Donley looked up and saw the opportunity for something remarkable. With an unbelievable piece of skill and audacity, having spotted Stefan Ortega had strayed a long way from his six-yard box, he went for the spectacular lofted chip from 40 yards out.

As soon as he hit it, you knew Ortega was in trouble – and so did he. Back-pedalling frantically, he was too far out from his own goal. On top of that, as the ball flew through the air with back spin, Donley had applied just about the right amount of speed on the ball. It was going to be very close.

Off the bar, then in off the keeper

As the ball started to drop, it looked like it was going to land perfectly into the net. Ortega had managed to get back close to his goal line but it was just too high for him to reach. He seemed to admit defeat but the ball hit the underside of the crossbar and bounced directly down. A collective groan formed in the throats of the Orient fans, but it was engulfed by a cheer as Ortega could not stop himself falling slightly backwards, directing the ball backwards into his own net via hand and calf.

BBC’s Richards questions if goal should have stood

Brisbane Road erupted in euphoria and disbelief as Donley sprinted over towards the West Stand to celebrate, followed by his team-mates. Barry Hearn, chairman of Orient from 1995-2014, was pictured beaming in the stands as Pep Guardiola’s men were left stunned.

Orient captain Dan Happe, interviewed pitch-side on the BBC at half-time, said: “Unbelievable – to score that against Manchester City is incredible. We just need to stick to it in the second half, embrace it and work our legs off.”

BBC pundit Micah Richards, on whether González, was fouled in the build-up, said: “They gave the ball away too cheaply but take nothing from the finish. If we had VAR maybe it would have been looked at.”