The Blues had been trailing 1-0 at the interval but an impressive second half turnaround was completed thanks to goals from George Swan, James Horsfield, Joe Nuttall and Jack Byrne.
Adam Sadler named a number of trialists in the starting line-up but there were some more familiar names in the side, including a back five of ‘keeper Liam Sharpe, Sadiq El-Fitouri, Ashley Smith-Brown, George Swan and Sam Jones.
There were some open mouths and camera phones were at the ready when the squad arrived at the impressive arena that was purpose built for Euro 2004 but as soon as the team pulled on the smart new Manchester City away kit, a sense of professionalism and focus naturally prevailed.
However, it was the home side who took the lead in the 34th minute, as Leiria punched a hole through the City defence and despite a decent save from Sharpe, the rebound was turned in by Carlos Daniel.
City made changes in the second half, installing Jack Byrne into the holding midfield position where he was always a willing recipient of the ball and showcased his extensive passing range to pull apart the Leiria resistance.
The improvement was rewarded in the 52nd minute when Captain George Swan maraudered forward from his centre back position and pulled the trigger from the edge of the area with a measured effort which curled past the despairing goalkeeper.
Sadler’s men pulled ahead courtesy of half-time introduction James Horsfield who capped a great team move with play switching sides before the midfielder met the ball on the half volley with a sidefoot finish.
The under-18s coach is a firm believer in putting players up an age group to provide a greater challenge and 15-year old Joe Nuttall was one of the boys included in the party for this trip and he marked it in style, scoring on his under-18s debut.
There was great work in the build-up to the goal with Byrne switching play out to Brandon Barker, who got past his full-back thanks to a good show of strength before beating the goalkeeper with his teasing cross, leaving Nuttall the simplest of tasks to head into the open goal.
The best was still to come in stoppage time and it was the cherry on the cake of a very impressive performance from Irish midfielder Byrne who cracked in a stunning strike from 30-yards which looped over the keeper into the top corner of the goal.
City will now face Benfica on Sunday, with several of the party who missed out this time around expected to make appearances.
