While Federer fell in three sets to Nishikori, Nadal made quick work of Mikhail Youzhny, 6-2, 6-3.
In the victory, Nadal captured 76 percent of first-serve points and 55 percent of second-serve points, according to ATPTour.com. He also won 67 percent of second-serve return points, saved two of three break points and converted five of 10 break points.
Nadal will now face David Ferrer in the quarterfinals. The 26-year-old owns a career 17-4 mark against his compatriot Ferrer, winning their last six matchups. Nadal defeated Ferrer in Acapulco this year, 6-0, 6-2. It took him just 65 minutes to do so.
So much for Nadal being a battle-worn athlete on the decline. All Nadal has done this year after missing the second half of 2012 with tendonitis is go 28-2 while racking up four singles titles. Since losing to Horacio Zeballos in his first tournament of the year, he's only lost once, to Novak Djokovic in the Monte Carlo final. He's also coming off a title in Barcelona.
Will Nadal win the 2013 Madrid Open?
Despite such a "devastating" injury in 2012, Nadal ranks in the top 10 this year in first-serve points won, second-serve points won, service games won, first-serve return points won, second-serve return points won and break points saved, according to ATPTour.com. He ranks 14th in break points converted. Not only that, he's dropped just eight sets in 30 matches.
Of course, Nadal still has Andy Murray to worry about. The Scot has gone 20-3 this season, with two singles titles. He blasted through the Sony Open, but he's also lost to Djokovic, Juan Martin del Potro and—most recently—Stanislas Wawrinka in Monte Carlo. A case can be made that Nadal is playing at a higher (and more consistent) level right now.
After all the gloom and doom for Nadal in 2012, who would have thought he would be playing at such a high level right now? Heck, Nadal doubted it just as much as any of us did.