No-one knows what might have happened had Gascoigne elected to join United instead of Tottenham when he had the chance in 1988.
"I have always said when Paul Gascoigne chose to go to Tottenham ahead of Manchester United it was a big mistake," Ferguson told Sirius XM.
"He always regretted that.
"He was a fantastic footballer. He was the best player England produced since the days of Bobby Charlton."