Europe captain Paul McGinley had been hoping to keep Ferguson's identity under wraps so it would come as a surprise to his players.
But the former Manchester United manager was spotted walking the grounds of Gleneagles early Tuesday — and McGinley could not keep the secret any longer.
"When I became captain, for a number of reasons, I asked him," said McGinley, who recalled playing with Ferguson in a pro-am about 15 years ago.
"Of course he was willing to help, but the one thing he asked me to do was keep it really quiet. And walking around ... is not keeping it quiet, is it, when he's onsite."
Ferguson retired as United manager last year after more than 26 seasons at Old Trafford, during which he won 38 major trophies.
Widely regarded as the greatest British football coach, he is also known for his temper and for delivering what became known as the "hairdryer treatment" to his players when he was unhappy at their performances.
"This is not about him being a headmaster and coming in and preaching to them," McGinley said. "This is about fun."
The news is likely to be welcomed by Rory McIlroy, the world No. 1 and a big United fan.
George W. Bush spoke to the American team on the Saturday night during the Ryder Cup at Brookline in 1999 — the year before he was elected president. During the speech, Bush read William Barret Travis' letter from a besieged Alamo with the powerful kicker: "Victory or death."
The U.S. team came from 10-6 down at the start of Sunday's singles matches to regain the cup that year, winning 14 1/2-13 1/2.