On April 21, 2001, Roy Keane planted his right boot into Manchester City's Alf Inge Haaland's knee, flattening the Norwegian.
Keane was sent off immediately for his horror tackle, received a three match ban and a fine of £5,000. The FA later extended the ban to five matches and also handed him a record-high fine of £150,000.
Keane revealed in an interview that he didn't feel any remorse for the incident, admitting the challenge was a deliberate attempt of vengeance after Halaand wrongfully accusing him of ''play-acting'' three years earlier. The Irishman said: ''My attitude was, what goes around, comes around. He got his just rewards. My attitude is an eye for an eye.''
Halaand accuses Roy Keane of faking an injury at Elland Road (EMPICS Sport)
The backstory of this notorious feud dates back to a 1997 tie between Manchester United and Leeds United. After 85 minutes Manchester United were a goal down and Roy Keane - notorious for his tantrums - attempted an unncessary tackle on Halaand. But the Irishman failed to make contact, and subsequently tore his cruciate ligament. And to add to his woes the United captain was booked for dangerous play.
Haalaand was sceptical of the true nature of Keane's injuries and shouted into the Irishman's pain-stricken face to stop acting and to get back on his feet. Keane was ruled out for the rest of the season, taking great offence at the Norwegian's remarks.
''Don't ever stand over me again sneering about fake injuries!'' (Telegraph)
It wasn't until 2001 that the duo faced each other again - and Halaand was now a player at local rivals Manchester City. As the derby match was heading towards a mundane draw, Keane exacted his revenge on Halaand. His deliberate knee high tackle resulted in an instant red card - but the United captain walked off the pitch with little remorse, smiling at the sight of his arch-rival limping off the pitch.
Halaand played only 48 minutes of professional football after this Keane tackle (YouTube)
Halaand never played a full match again following that incident and was forced into early retirement in 2003 at just 31 years old. Even though it was his other knee that ultimately ended his career, Halaand blamed Keane's tackle for cutting his career short. ''Did that tackle end my career? Well, I never played a full game again, did I? It seems like a great coincidence, don't you think?" the Norwegian said in an interview in 2007.