The former football manager's seven-man team included his wife Cathy, millionaire businessman Willie Haughey and a few relatives.
Opposing teams at the quiz on Thursday night at the Burnside Hotel near Glasgow thought they were facing a heavy defeat due to the former Manchester United supremo's reputation for being a quiz fanatic.
However, Sir Alex's team ended up coming third. He went on to jokingly brand the winning side "a bunch of cheats" before warmly congratulating them and spending time posing for photographs with regulars and other team members.
One member of the winning team said: "I've been going every Thursday night for about the last 14 years. But I couldn't believe it when I saw that Sir Alex had entered a team.
"His wife Cathy was also in it and Willie Haughey, who owns the hotel. Not surprisingly Fergie was really competitive and you could tell he was really into it.
"He kept asking for questions to be repeated. But he was also involved in banter with other tables and having a laugh and a joke."
It is understood Sir Alex and his family were staying in the hotel in preparation for the wedding of his great niece yesterday.
Former Scotland manager Craig Brown once advised people never to oppose Sir Alex in a pub quiz, describing him as highly intelligent with an extraordinary memory.
Former Manchester United striker Andy Cole also revealed how during his time at the club, Sir Alex ran fiercely contested quizzes that he "fiddled" to ensure he always won.
He said his then manager's quizzes were legendary at Old Trafford and were often incorporated into a European away trip to help pass time.
Cole said: "The thing was, the gaffer usually came up with the questions - or got someone to - and then he had all the answers.
"Then he had this amazing way of managing to get the points from a question when the other team were conferring.
"The manager is used to winning - and it was not any different with a quiz. He was the final arbiter and when we lost, we always came out gutted because we knew the manager would have fiddled things in some way to make sure he won."
The Burnside Hotel declined to comment.