Rory McIlroy reacts on the 18th green after an eventful third round, in which his six-shot advantage was wiped out Credit : Hector Vivas/Getty Images Rory McIlroy’s six-shot lead was whittled down to naught here on Saturday. Yet if that sounds as if it was a terrible day for the defending champion then that belied the relief on his face as he finished this madcap third round. In truth, he was simply glad to still be in contention after so many mistakes. “I didn’t quite have it today,” McIlroy said, with almost comical understatement. “I will have to play better if I want to have a chance to win tomorrow.” In a wild, low-scoring drama on a layout softened by the generous, if slightly baffling hosing of the Augusta greens, McIlroy contrived to squander his huge advantage and actually fall behind. And then with back-to-back birdies on the 14th and 15th, he thrust his way back to the top. But then he lost it again. It was exhausting, excruciating even.…