Researchers have been asked to study the impact of Rangers and Celtic on wealth and spending power in Scotland.
Football fans spend millions of pounds
Greater Glasgow and Clyde Valley Tourist Board commissioned Strathclyde University's Fraser of Allander Institute to carry out the work.
Professor Kim Swales, who is in charge of the project, has promised "a report of two halves".
He said it will look at the clubs' direct economic activities as well as the knock-on effects.
Eddie Friel, chief executive of Greater Glasgow Tourist Board, said: "Rangers and Celtic are two of the biggest brands in world football and make an enormous contribution to the life of the city.
"The Old Firm clubs play a key role in attracting visitors to Glasgow and reaching audiences around the world."
The study has been commissioned to look at how much fans spend on match days and will cover supporters from Glasgow, Scotland and beyond.
Professor Swales said: "This will be the most detailed investigation of the full economic impact of major football clubs in the UK."
Both Old Firm teams are backing the research.
Rangers chairman John McClelland said: "We are pleased to see our economic contribution to the community being recognised.
"Over and above the value created weekly by the club, our Champions League participation obviously generates additional economic benefits for Glasgow and recognition for the city."
And Celtic chief executive Peter Lawwell said: "Total attendances at Celtic Park this season have already broken the one million barrier and the additional economic spin-offs from away fans attending the many European nights we've played in recent years are enormous."
The Tourist board is hoping to base new efforts to promote football-related visits to Scotland on the results of its research.
Mr Friel said: "Other cities such as Barcelona and Manchester are using football to boost their international profile and economy and Glasgow should do the same."