Andy Flower's twin 142 & 199* against South Africa when he scored something like 68 % of Zimbabwe's runs. Only one other Zimbabwean in each innings made more than 30. He came out to bat on 51-3 and 25-3. After the first knock, he asked Shaun Pollock if he was going to enforce the follow-on. Pollock said "yes, of course". Flower just said "good". Apparently, he didn't play a false shot all game, apart from being dropped on 197* in the second innings. In fairness, it was a flat pitch, it was just the rest of Zimbabwe's players (with the exception of Ebrahim and Masakadza who made 71 and 85) were clueless. They still fought it out though. Flower wouldn't have got near that 200 if it wasn't for Douggie Hondo, on debut, sticking it out for an hour.
Jack Hobbs and Herbert Sutcliffe's 100 and 161 respectively on a really difficult track at the Oval in 1926; the match report read:
"Finer cricket on a difficult wicket than Hobbs and Sutcliffe played I have never seen. Much, almost everything, indeed, depended on them. If one or both had failed, England might easily have lost five or six men before lunch, for the ball took the spin quickly, and when the sun--which at first hid its face--came out after the first hour, the ball, particularly from Richardson's bowling, kicked up frequently in a disconcerting manner."
And for New Zealand, very little tops Bert Sutcliffe's 80*- that story always brings a lump to my throat.