Of course nadal hasn't lost a set but has been to 3 breakers thus far. Lopez has looked decent but did get pushed to a 5th in the 2nd round and then basically a walkover last round.
IMO nadal has looked good but not untouchable. His serve is much improved but has had some control issues on the forehand whether it's the wind or ball.
To me the odds seem way off as Lopez a 10-1 dog as he beat nadal earlier this year On grass and played him pretty close in their careers. With some windy conditions already today this could be a better shot for Lopez here.
I know it's still not likely but I think nadal could be exiting early tonight.
I agree that the wind does not benefit Nadal at all. However, you should know that Nadal gave lopez that win earlier this year- he lost on purpose. Nadal is not untouchable with the speed of these courts at all, but Lopez will not beat him in a slam.