PUBLIC health experts say they have conclusive proof of a link between domestic violence and Old Firm matches.
The study, by researchers at St Andrews University, is the first to confirm long-held beliefs that reports of domestic violence in Glasgow increase after matches between Rangers and Celtic.
The new paper shows a "statistically significant" rise in domestic incidents following all 21 Old Firm matches between 2008 and 2011.
Researchers say the study provides "compelling evidence" of the effect of Old Firm matches on reported domestic cases of physical, sexual and emotional abuse in the 24-hour period after kick off.
The study was led by Dr Damien J. Williams, a lecturer in Public Health Sciences.
He said: "Media reports have long suggested that the number of reports of domestic violence appear to increase when Scotland's two largest, Glasgow-based football clubs, Rangers and Celtic play one another.
"These have followed concerns by the Scottish Government who say that domestic abuse in Scotland is an increasingly visible problem, with the highest prevalence on females in Strathclyde."
Statistics indicate a year-on-year increase in incidents of domestic abuse reported to the police between 2002 and 2003 (35,877) and 2011 and 2012 (59,847).
The majority of these incidents occurred in the old Strathclyde Police jurisdiction, with the majority of victims being female.
Dr Williams added: "Our aim was to develop a robust analytical approach to undertake a preliminary exploration of the association between Old Firm matches and reported domestic incidents in the Strathclyde Police area."
Previous studies have examined abuse of partners by male athletes, while others have looked at the link between sporting events and increased domestic violence - thought to be the effects of the toxic combination of sport, alcohol and heightened masculine behaviour.
In the new study, Dr Williams worked with St Andrews graduate Kirsty House and St Andrews' colleagues Dr Fergus Neville and Professor Peter Donnelly.
The researchers looked at the number of reports of domestic violence incidents to Strathclyde Police following an Old Firm match.
Reports were based on any form of abuse against a partner, or ex-partner, in the home or elsewhere. Dr Williams added that the figures gave a "conservative estimate" of the problem as incidents would be unreported.