no, he didn't.
Djokovic had just beaten Murray in a good quality Doha final before AO 17. They were the 2 favorites for the AO.
Go refresh yourself. No long sleeve:
Djokovic did have significant injuries from mid-2017 to couple of months in 2018 including vs Chung at AO, but not in AO 17.
Not just nadal, fed also beat Wawa. Remember, the same Wawa who was Djokovic's nemesis in slams from 14-19 going 4-1 vs him in slams in that period.
Fed's AO 17 of Nadal, Wawa, Nishi, Berdych is like a gazillion times tougher than Djokovic's AO draws from 19-21.
If djokovic faced fed in the form that he displayed vs Istomin, he's going to lose.
the last statement is not relevant to what I am saying (not that its necessarily true)