I don't think the Djokovic problem is present anymore.Djokovic: looks good, but really only opens up after winning the 1st set.
Nadal: looking to be more offensive; making more UEs as a result (which isn't such a bad thing)
Federer: looks good, but I too early to say especially against rhythm-stealing players like Karlovic
Murray: looks good as well.
Of anyone, I'd say Nadal looks the weakest since he seems to be in the middle of slightly tweaking his game
Lost a set to Harrison. Looked better next round. Just gets an alright for me.. I thought Nadal played well against Lacko.. The next round will be more telling of his progress and his potential to win .I think Murray looks better than allright and with Nadal is always an uphill journey. He gets better as the tournament progresses.