It was the second straight match in which Nadal needed four sets to advance. Daniel Brands and Klizan were each able to win the first set from the 11-time major champion, but Nadal bounced back strong to take the next three sets each time.
Although his track record suggests he deserves the benefit of the doubt, the mundane results (by his standards) are starting to grow worrisome. A more convincing performance against Fabio Fognini in Round 3 would restore full confidence in the Spaniard.
One concern until he displays top form is the extra mileage he's racking up to win these early matches. Don't forget, Nadal is only a couple of months removed from an extended absence due to lingering knee issues, so every extra set takes its toll.
Normally, Nadal would breeze past opponents like Brands and Klizan without breaking a serious sweat. Instead, he's been forced to play from behind in both matches.
Getting off to a quicker start in the Fognini match should be his main goal. Playing from behind against early-round foes is survivable, but he's playing with fire if he keeps starting slowly as the level of competition begins to increase.
Looking ahead, Nadal remains on a semifinal collision course with fellow superstar Novak Djokovic. When you consider Roger Federer could also be waiting in the final if the seeds hold, Nadal needs to be preserving as much energy as possible right now.
All told, even though "The King of Clay" will be happy to advance, there's definitely room for improvement. He isn't playing anywhere near the same level tennis fans have seen from him in years past, but he still has time to reach that level.
If history is a guide, expect to see signs of progress against Fognini in the next round.