In 1987, in the middle of his first full season as United manager, United Somerset Trojan of Bermuda while on a tour of the Caribbean and a 45-year old Ferguson, along with his assistant Archie Knox, then 40, were introduced in the second half.
According to Yahoo Sports, Knox scored a 35-yard screamer for the final goal of the game, while former Falkirk, Rangers and Ayr United striker Ferguson, comfortably the oldest player on the pitch, went close with a header in a 4-1 victory.
That was his only one appearance as a United player, but there is an even better story of Fergie bringing himself on an earlier friendly over in the Caribbean.
In his second stint in management with St Mirren, Ferguson took his players on a three-week pre-season tour.
As per Thore Haugstad, writing in Four Four Two, the outing came about because former chairman Harold Currie, had business links in the trading of whisky.
But it wasn't just a big three-week piss-up for Fergie's men as they played some friendly games, one being against the Guyana national team ahead of a big World Cup qualifier that was on the horizon.
The story goes that the Guyana team were not taking it easy at all, their centre-half being very rough and ready with the Saints' young forward Robert Torrance - something that angered Ferguson and prompted him to remonstrate with the referee from the touchline.
When Torrance was done in again by the same player just before half-time, Fergie's head went and he wanted a piece of the defender.
"That's it, I'm coming on," Ferguson said to his assistant David Provan.
"That big bastard is taking liberties."
1/12/87 Alex Ferguson makes his one & only appearance playing for Man Utd. The game was a mid-season friendly v Somerset Trojans at the Somerset Cricket Ground, Bermuda. Fergie (age 45) came on for Peter Davenport 21 mins from time. Utd won 4-1 (Wilson McClair Archie Knox Olsen) pic.twitter.com/wlNz6ha3fK- Pete Molyneux (@PeteMolyneux) July 7, 2020
Provan and Ferguson had both been kitted out as substitutes for a laugh but now that things had got real, the fiery Scotsman wanted in and would not let his right-hand man stop him from doing so.
He entered the fray and when the next cross came in, Ferguson exacted "a bit of revenge" on the defender, leaving him "squealing" - according to the man himself.
When they went at it again, Ferguson left it on the centre-back one more time and the referee swiftly sent him off. Afterwards, he warned his players to remain tight-lipped about his dismissal.
No wonder he ended up getting 17 touchline bans at United...