It's difficult to understand the magnitude without some knowledge of cycling. But...on Wednesday, Landis hit the wall going up the final mountain of the second stage in the Alps and lost ten minutes of time (10:00 with four stages left is the equivalent of being down, say, 5-0 in a hockey game with 5 minutes left in the third), enough that everyone who follows cycling conceded that he had no chance of winning the Tour. The very next day, he went off on a solo breakaway over all four mountains in the next stage and got all but 30 seconds of that time back. Normally, riders attack on the final hill -- attacking before they even reach the first hill is unheard of, practically suicidal.
It's probably the greatest ride in cycling history.