Huddersfield Town legend Denis Law collapsed on a plane at Manchester Airport.
The 76-year-old former striker, who is now recovering from his ordeal, told how he suddenly felt faint then slumped over in his seat ahead of a family holiday.
He was with his wife Diana about to fly to Menorca in Spain for a sunshine break.
Mr Law was taken to Trafford General Hospital in Manchester, where he was later released after checks and tests.
Doctors reportedly diagnosed the problem as a possible vasovagal attack - a sudden fainting episode caused by a number of different triggers.
Ex-Scottish international Mr Law began his career at Huddersfield Town in 1956.
After four years with the Terriers he was signed by Manchester City for £55,000, setting a new British record.
He spent a year with Italian side Torino before moving to Manchester United in 1962 for a fee of £115,000, setting another British record.
He scored 237 goals during his 11-year stint with the team and was one third of what became known as Manchester United’s Holy Trinity, when he played alongside George Best and Sir Bobby Charlton.
Mr Law, who was awarded a CBE at Buckingham Palace in March for his services to football and charities, told a national newspaper: “I went white and did not feel well at all.
“The next thing I collapsed while in my seat.
“I feel better now, but I’m having tests as it’s happened a few times in the past few years.
“It’s not pleasant. One time I thought I’d snuffed it. Hopefully I’ll be able to join the holiday soon.”
Mr Law, a father-of-five, is a fundraiser for Cancer Research UK and a patron for the charity Meningitis Now.
He made a recovery from prostate cancer in 2003.
“I felt foolish when I came round on the plane,” said Mr Law. “I just conked out. There were nine of us on the plane.
“It was a nightmare and it’s worrying.
“We’d got up at 4.30am for the flight so that probably didn’t help. It just happened so quick but I feel a lot better now.”