Im sure Djokovic had a plan in Rome also. It really just depends where his game is at whether he can execute or not.
When they are both top of their game, Djokovic is favourite on anything but clay IMO, but I don't think hes at his best right now, whereas Nadal has actually looked better here than he did in RG in my opinion ( as crazy as that sounds ).
What I mean by that, is that he wasn't as mind blowing at RG as 2017, but his grass form is way up on last year ( even though he was good last year too ).
I think confidence matters more to Nadal, and with the recent wins over Novak ( albeit a less than perfect Novak ), he will be feeling very confident.
Djokovic has to shake Nadal early, and make him doubt himself. If Nadal gets ahead, I feel its only going to go one way.