He's won MC, Barcelona and Rome in straights. Madrid and it's blue clay was the one aberration. Winning titles without dropping a set isn't easy so wel done Rafa - clay God in business so far this season.
Last player to take a set off him on red clay - Del Potro.
"Who ain't a slave? Tell me that. Well, then, however the old sea-captains may order me about—however they may thump and punch me about, I have the satisfaction of knowing that it is all right; that everybody else is one way or other served in much the same way— either in a physical or metaphysical point of view, that is; and so the universal thump is passed round, and all hands should rub each other's shoulder-blades, and be content." - Herman Melville, Moby Dick
Only Federer in the Roland Garros final (7-5) and Del Potro in the Davis Cup Final (6-1) managed to take sets off him in this period. Quite impressive, he hasn't even played that many tiebreaks either.