Football is one of the most popular sports in the world. It has existed since 2013, when the Scottish Premier League and the Scottish Football League merged into the SPFL. McConnell, Alison (11 June 2015). “1970 European Cup Final: Lisbon Lion Craig said Celtic were ‘too cocky’ in defeat by Feyenoord”. McConnell, Alison (10 June 2015). “1969-70 European Cup: Celtic on road to final after flip of a coin and Battle of Britain victory”. Gordon, football tops Moira (27 April 2017). “Scottish football didn’t care as Third Lanark slipped away”. Henderson, Gair (28 April 1969). “Celtic put trophies on parade”. Manchester United has also consistently enjoyed the highest commercial income of any English club with big sponsors like Nike, Sharp Electronics, Vodafone, and AIG.