Pep Guardiola's delight at Claudio Echeverri's maiden City goal quickly turned to concern after the teenager picked up a knock that threatens his involvement against The Old Lady on Thursday.
The 19-year-old Argentine prodigy marked his first start for City with a sublime free-kick against Al Ain, curling home a set-piece inside 30 minutes to extend the lead after Ilkay Gündogan's opener.
While Al Ain's defensive wall left plenty to be desired, Echeverri's execution was flawless – the result of countless hours perfecting his craft long after teammates had called it a day.
"He stayed behind after every training session last season to work on free-kicks alone," Guardiola revealed to DAZN. "Hard work always pays dividends. Goals don't come by accident – they come from practice."
The promising start unravelled at the interval when Guardiola was forced to withdraw his young talent, bringing on Phil Foden for the second half. What initially appeared tactical proved medical, with the City boss confirming Echeverri had sustained an injury that could rule him out of Thursday's group stage decider.
"Such a shame about the twist," Guardiola said. "He's feeling some discomfort. The problem emerged at half-time, which prevented him continuing. He possesses real quality in tight spaces and produced a brilliant finish."
The setback represents a frustrating interruption to what had been a perfect introduction to senior football for the South American prospect, following his late cameo in the FA Cup Final. Having arrived with considerable fanfare, Echeverri's debut goal suggested he could quickly establish himself in Guardiola's plans.
City will now wait on the severity of the injury, with Thursday's fixture against the Italian giants looming large.