Watch: Ruud van Nistelrooy brilliantly takes the piss out of old enemy Martin Keown

He may be retired, but Ruud van Nistelrooy is as sharp as ever.

The Dutchman was one of the most prolific strikers of his generation, scoring 75 goals in 95 games for PSV, 150 in 219 for Manchester United, 64 in 96 appearances for Real Madrid and 35 in 70 games for the Netherlands. He proved in this video that he's as quick witted as he was sharp in front of goal. The 39 year old was at the Oxford Union recently, engaging in an hour long interview, and it didn't take long for Martin Keown to be mentioned. The former Arsenal defender infamously goaded Van Nistelrooy after the United striker missed a last minute penalty against the Gunners in September 2003.The Arsenal players accused Van Nistelrooy of diving to earn the penalty, and as a result of the melee following the missed penalty, a number of players from both sides received fines and suspensions from the Football Association. When told that his old nemesis Keown, who landed something of an elbow on the United striker whilst celebrating his penalty miss, lives in Oxford, Van Nistelrooy couldn't pass up the chance to question the former England defender's intelligence. https://www.youtube.com/watch?v=G2eiUvqjVx0