Martin Buchan (456 appearances, 1972-83): United's star player of the 1970s, Buchan provided an almost flawless presence in central defence for over a decade. Signed from Aberdeen for £125,000 - a bargain, even back then - the Scot quickly established himself as an outstanding member of a team struggling under Frank O'Farrell. Blessed with blistering pace and insightful reading of the game's finer details, he was by far the most consistent performer in the Reds' ranks. A driven individual who insisted on fearsomely high standards, Buchan inspired the respect of his team-mates and performed a masterful shackling job on Kevin Keegan in the 1977 FA Cup final.
Rio Ferdinand (454 appearances, 2002-14): Often described as a 'Rolls Royce' of a defender, the naturally gifted footballer combined athletic grace with unflappable composure. Although he first came to Sir Alex's attention during a loan spell at Bournemouth, the centre-back was able to fulfill some of his huge promise at first club West Ham United before securing a record switch to Leeds United. It says everything about Ferdinand that the Reds' £30million outlay,