Monaco vs Nadal is partly match-up but also partly the fact he's so in awe of him he just rolls over like a girl. Nieminen, Ferrer, Simon, Benneteau, even Boredo, are all players with limited weaponry who have given Nadal either defeats or tight contests so I don't see why Monaco couldn't.
Even Devvarman kept it closer when he played Nadal
Speaking of Nadal, his matchup with Dolgopolov is a good example here. For starters, Dolgo is far too erratic for perhaps the steadiest baseliner in tennis history who will give no points away. As if that were not enough, Dolgo slices far too much: there's basically no more suicidal tactic in tennis than slicing to Nadal's forehand (even Federer has fully abandoned that tactic), Nadal accelerating those balls with his forehand. Results: 6-4, 6-3, 6-1, 6-2, 6-3, 6-2.