Just over an hour into this cup tie, Nico O’Reilly received the ball close to the left touchline, looked up and calmly attempted a long crossfield pass that floated out of play.

It was about the only thing he got wrong all evening.

The teenager had already headed his team back into the game after Plymouth Argyle threatened another giant slaying, and his influence — even playing out of position at left-back — was manifest.

Some young players might have had a drop in confidence at such a moment, but O’Reilly was swiftly back on the ball as if nothing had happened.

Just under 15 minutes later, he ensured City’s comeback with another clinical header.

Last summer Pep Guardiola said of O’Reilly: “He’s a guy who will be a player. He will be a player,” and in this reassuring FA Cup win at the Etihad, it was abundantly clear what the Manchester City manager meant.

City have got a real player here. No wonder the club decided not to sanction his sale to Chelsea in the winter transfer window.

Guardiola and co did not want another regrettable sale in the Cole Palmer category, and while O’Reilly is some way behind his fellow Mancunian in development, it is not too fanciful to imagine him having a similar impact.

Elegant on the ball but also big and strong, O’Neill, who stands at 6ft 2in (188cm), is a well-rounded performer with many strings to his bow. He can ping an inch-perfect pass 40 yards, finishes confidently and can hold his own physically.

Witness the way he dominated Jordan Houghton, much to Plymouth’s ire, as he beat the Argyle substitute, who is 10 years his senior, to score his second goal of the contest.

While O’Reilly announced himself to the wider footballing world with his man-of-the-match display against a team that had already knocked Liverpool out of the cup, he has been the subject of Guardiola’s close attention since watching him on a U.S. pre-season tour in 2022. One of a clutch of youngsters included in the squad for that pre-season, he shone the brightest and impressed the coaching staff with his decision-making and maturity.

This season the FA Cup could be both City’s consolation and a springboard for the 19-year-old to become a regular pick for Guardiola’s team.

He was among the scorers in the 8-0 hird-round thrashing of Salford City, and that impressive debut, also at left-back, earned him his Premier League bow with 18 minutes in the 6-0 win against Ipswich, then a brief cameo last month at the end of the triumph against Newcastle United.

“Sometimes you take a good decision,” said Guardiola after the 3-1 win on Saturday, responding to a question about not selling the former academy star during the January window.

Then the City manager summarised why physical outlier O’Reilly stands out, in every sense, at the moment.

“He’s not typical of the academy players because all the academy players are so small and skilful but he has a big big presence,” he said. “Normally he is an attacking midfielder, a No 10 who arrives in the box really well but, for the problems we have, he adapted really well as a full-back.

“I think can play as a holding midfielder and he’s a threat at set pieces, where he can help us. We are not a tall team and so he helps us. He played really good with the ball, without the ball and got two fantastic goals.”

Impressively, left-back is O’Reilly’s third role as a senior player for City already. He has previously been deployed as a holding midfielder, but has been an attacking midfielder since he started with City as an under-six, a background that aided his quick adaptation to a deeper role.

His unflappable nature, evidenced by his reaction to that mishit pass, could ensure he continues to capitalise on exposure to City’s first team in pressurised moments such as trailing to a Championship side at home in the FA Cup.

After the comeback win, Guardiola’s face lit up when he talked about the possibility of Rodri’s return ahead of schedule before the end of the season, perhaps even for a Wembley visit, should City earn it.

But before then, it would be intriguing to see what O’Reilly can do in a central-midfield role. Guardiola has previously said he could potentially fill in for the Ballon d’Or winner and, given his contribution from left-back, it is an enticing prospect.

A difficult season at the Etihad still has flashes of promise: both in the FA Cup and in the potential of this local lad who has grabbed his time in the competition so far with both hands.

Capable of being a big presence on the big stage, if O’Reilly can build on this momentum he might just be a factor in helping City change the narrative.

(Photo: OLI SCARFF/AFP via Getty Images)