Football historian Gary James has revealed that Manchester rivals United and City considered merging back in the 1960s.
The proposal was made by City chairman Frank Johnson but was quickly rejected by the United board.
Both clubs were going through a tough time, with United still recovering from the 1958 Munich air disaster and City experiencing record low attendances while playing in the second division.
"The idea was killed by the clubs before it ever became public," James said.
"I spoke to Eric Alexander, whose dad Albert was also chairman around the time. He said that Frank Johnson, who proposed the merge, was always coming up with crazy ideas."
United and City currently sit level on points in second and third respectively in the Premier League table.