The 53-year-old star proposed to his girlfriend Amal Alamuddin last month and although rumours had suggested he was planning to ask Brad Pitt to be his best man, it's now been revealed that he's chosen his 'The Monuments Men' co-star instead.
A source told The Sun newspaper: ''A lot of people thought Brad was a certainty to be George's best man as they have been such good friends for years. But he is probably even closer to Matt.
''Besides many years ago, during one drunken night together, George made a promise to Matt that he would make him his best man if he ever got married - so Matt called to claim his prize.''
However, as 50-year-old Brad worked with Matt, 43, and George on 'Ocean's Eleven' and it's sequels, it's thought that the hunk will be there to support both of his pals.
The source added: ''Brad took the news with good grace - but he did say he'd heckle Matt during his speech.''
Meanwhile, George is reportedly planning to throw his British lawyer fiancée the wedding of her dreams either at his home in Lake Como, Italy or Cabo San Lucas in Mexico, before relocating to London so that she can continue her work as a barrister at the Doughty Street Chambers.
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