The South Korean defender was caught by a studs-up tackle from City's David Sommeil and was stretchered off with a knee injury.
Initial reports from the City of Manchester Stadium suggested he'd suffered bad bruising but Head Coach Martin said afterwards: "We're not sure how serious it is and we have to scan him.
"It was a horrific tackle and Young-Pyo said that he'd never experienced a foul like that.
"Hopefully he will be fine but if not we have a problem."
Young-Pyo Lee is set to undergo scans to determine the extent of the knee injury sustained at Manchester City on Wednesday night.