Roy Keane and Alan Shearer both enjoyed hugely successful careers. The former captained Manchester United and won 17 trophies during his time at Old Trafford, while the latter, who also captained his side, is still the all-time Premier League top goalscorer and famously won the top-flight title with Blackburn Rovers in 1995.
The pair followed a similar path after the conclusion of their playing days, which included stints as managers - albeit only as a caretaker in Shearer's case - and more recently, in punditry. Keane is currently one of Sky Sports' most popular and explosive pundits, with the Irishman also occasionally working for ITV Football. Shearer, meanwhile, is one of the BBC's biggest names.
Given that United were considerably more successful than Blackburn Rovers, and later Newcastle United, the rivalry that began to develop between Keane and Shearer came as somewhat of a surprise to many people. Two of the league's most prominent figures had somehow become on-field enemies.