Newcastle midfielder Siem de Jong feared he could lose the sight in one eye after a freak training ground accident, said boss Steve McClaren.
The 26-year-old Dutch international was rushed to hospital with blood pouring from the eye on Wednesday.
However, while he faces up to two weeks out, a relieved De Jong has been told he should make a full recovery.
"It was just in training and he accidentally got poked in the eye," said McClaren.
The Magpies head coach was attending the memorial service for former Newcastle goalkeeper Pavel Srnicek at the time of the incident.
McClaren said of De Jong: "He went down screaming, so they said 'Let's have a look at your eye' and there was blood pouring from it.
"He wears contact lenses, and one of the contacts had come out and gone into his eyes."
Asked whether there was a fear De Jong could have been blinded, McClaren replied: "Yes, yes, a massive danger, a big danger. He was rushed to hospital.
"I've seen him this morning and it looks a lot better. Fortunately, the doctor says [it needs] probably a week or two to settle down, so he's very lucky."
The accident is the latest misfortune to hit De Jong, who has made just 22 appearances, only seven of them starts, for the club he joined from Ajax during the summer of 2014.
His fitness problems to date include a collapsed lung - the second of his career - which sidelined him for two months last season.