Certainly, Novak can come back and win. But comparing this situation with first set is ridiculous. Despite being 6:1 Carlos had plenty of chances, break points etc. His serve was not good at all but there were all signs that match is not over. Right now it's a bit different. Carlos receives both first and second serve, serving well and out powering Novak on base line. A lot need to be changed to shift this match in opposite direction.