Actually,Djokovic was very disappointed with his game yesterday. I read the Serbian newspaper this morning (obviosly i'm from Serbia) with an interview with Novak where he stated that he doesn't even know how he won the second set.
Also,he said that is very hard to focus on tennis with other things on his mind.
He's definitely not satisfied with his game or with his form entering in RG. So,i wouldn't say that Novak tanked the match yesterday.