On 6 August 2003, Manchester United lost to Sporting in a friendly that introduced them to the Portuguese side's dynamic young winger, Cristiano Ronaldo.
United were in Lisbon to help Sporting inaugurate their new home, the Estádio José Alvalade. The Red Devils had just completed a four-game tour of the United States and seemed to be suffering from tired legs as the hosts romped to a 3-1 victory with goals from Luís Felipe (26') and João Pinto (62', 81'). Even United's consolation goal came courtesy of the Portuguese, as defender Hugo put the ball into his own net with two minutes remaining.
The day wasn't a total waste for United, though. Afterward, several players spoke to manager Alex Ferguson, raving about the performance of Sporting's 18-year old midfielder, Ronaldo, and urging their boss to sign him. Although Ronaldo had already attracted the interest of Arsenal and Liverpool, United swooped in and signed him that summer for a fee of £12.24M.
Ronaldo remained at Old Trafford for six seasons, making a total of 292 appearances in which he scored 118 goals. Along the way, he helped the club to three consecutive Premier League titles from 2007 to 2009 and won the Champions League in 2008.
In the summer of 2009, Ronaldo moved to Real Madrid for the world-record transfer fee of £80M, a profit of almost £68M for United.