I'm not a sportsman so I don't really know the answer to this, but watching Murray 5-1 down in the 3rd, but 2 sets to the good and with Seppi serving. Do you just think 'f**k it' and lose that game to conserve energy and get on with the 4th set?
I don't think Murray did this even though he did lose that game and smashed the 4th set. I was thinking 'just lose it and save energy', but I'm a fat lazy bastard.