He turned 20 years ago and has played just 23 minutes in the Premier League this year. Yet Nico O’Reilly is the reason why Manchester City did not exit the FA Cup and overturned Bournemouth, winning 2-1 to reach the semi-final at Wembley on 26 or 27 April against Nottingham Forest (the other is Crystal Palace-Aston Villa, who won 3-0 at Preston North End thanks to a brace from Marcus Rashford). The reason for the turnaround, the reason why the team adrift and struggling against Bournemouth’s dreams in the first half transformed into the winning team in the second half, are the forays down the left by this young man who finally made his teammates understand how Pep had intended the starting 4-3-2-1.

In a bid to add life to City’s play, Pep Guardiola replaced Abdukodir Khusanov with Nico O’Reilly at halftime. The young midfielder slotted in at left-back for the second half. He proceeded to put in a match-winning performance to help Manchester City pick up a 2-1 win over the Cherries. In the process of helping City turn around the FA Cup quarter-final tie, Nico O’Reilly showed that he is ready for a bigger role at Manchester City going forward.

Nico O’Reilly made an immediate impact off the bench at the Vitality Stadium . His rampaging run down the left was picked out by Kevin De Bruyne.

O’Reily is the inspiration for the goals of Erling Haaland first and then Omar Marmoush, the perfect substitution that turns everything around.

The spirited Guardiola has repeated several times that winning the FA Cup would not change the disappointment of this season, but the cup in which City will play the semi-final for the seventh year in a row could be a small consolation. Like the reaction in the second half that transforms the dull and demoralised City of the first half into the team that deserves the victory.

O’Reilly with his forays down the left made the difference, waking up a group that in the first half hadn’t understood that the success of the 4-3-2-1 with Foden and De Bruyne behind Haaland could only work with the full-backs’ push. Or with more movement from the attacker, brought in immediately by Omar Marmoush after replacing the injured Haaland. Guardiola’s team was so disastrous in the first 45 minutes that Haaland missed three chances, including the penalty kicked badly into Kepa’s arms in the 14th minute.

Bournemouth deservedly advanced and tried to take advantage of City’s weakness, especially mental weakness, but the first goal fizzled out immediately and they didn’t understand that the resurrection of Guardiola’s team would come from the left wing. It remains an excellent season for the Cherries, one to try to close by conquering Europe for the first time in their history: Iraola's team will have to move on from the championship now, because the idea of passing the quarterfinals of the FA Cup for the first time in their history foundered in the second half, with the incursions of a 20-year-old who has played just 23 minutes in the Premier and who has been able to revitalize the team of lost champions.

Bournemouth fades, City takes control of the game and in the 82nd minute hits the post with a nice shot from outside by Gündogan: to go to Wembley to play the semi-final of the FA Cup at the end of April, even 2-1 is enough.