Roy Keane: When Man Utd icon mugged off Ronaldo and Diego Simeone vs Inter Milan in 1999

Roy Keane is a law unto himself.

Whether it's been as Manchester United's all-conquering captain or Sky Sports' go-to pundit, the Premier League legend hasn't been afraid to behave in exactly the sort of manner that he sees fit.

That's not a criticism, by the way, because Keane's no-nonsense and uncompromising methods almost certainly played a crucial role in his rise as one of British football's finest ever leaders.

You only have to look at the respect his former United teammates hold for him and the fear that he instilled in his old rivals to see just how formidable Keane was when he crossed the white line.

And that rule applied even before a ball had been kicked with the Irishman looking like he wasn't to be messed with from the moment that the players lined up in the tunnel to take to the pitch.

You only have to ask Patrick Vieira to discover that Keane was more than willing to stand up for his teammates and intimidate his adversaries long before the first whistle had even sounded.

And one of the finest ways that Keane's daunting persona on the pitch manifested itself was during a Champions League clash with Inter Milan during United's famous treble-winning campaign.

Before the Red Devils could dream of glory with their dramatic comeback at the Camp Nou, they were making the intimidating trip to the San Siro for the second leg of their quarter-final tie.

United already had the contest under control after a 2-0 win at Old Trafford, but it quickly became apparent that Keane didn't want to waste any time in getting the return leg underway in Italy.

That's because Keane produced one of his most amusingly ruthless moments in a United jersey during the traditional handshakes before kick-off by snubbing Diego Simeone and