The bad blood and hooliganism between the pair is very well known, as are some famous transfers from one to the other (Eric Cantona, Rio Ferdinand to Man U, Gordon Strachan to Leeds). Just as well known is Leeds amazing fall from grace -- relegation, financial collapse and administration, and then further relegation to the third tier.
Well Leeds finally looks on the rise, leading League One by 8 points and looking a good bet to be promoted to the Championship, one step closer to the Premiership. In the meantime, battles like today's against Man U will remain rare, but they can still be special. With the visiting Leeds fans helping to make the Old Trafford atmosphere a lively one for an FA up third round tie, Leeds came away with a famous 1-0 victory.
Sir Alex will be concerned with the continued uneven performances of his squad, but for a day it's good to see an important, historic club regaining its foothold, with a complete re-emergence hopefully coming soon. There's really no way to equate the Leeds story line to anything in US sports without relegation, and in some way that's a great benefit of US sports. Some teams have come and gone, moved and been re-born (sticking with just recent history, the Zombie Sonics, Cleveland Browns and Baltimore Ravens, Montreal Expos/Washington Nationals) but it's not likely that a franchise with the equivalent proud history of Leeds would suffer such indignation (MLS is excluded from this, anything goes with MLS franchises, sad as that is. And no matter how much the NHL or NBA is struggling, the marquee teams aren't disappearing.)
On the flip side, it's also impossible to have a similar story of re-birth, nor is the sporting system set up to allow a low level professional team the opportunity to even play, let alone upset, the sport's reigning giants. Just another reason why it's the world's greatest game.