Between last November's ATP World Tour Finals and this week's Doha tournament, Rafael Nadal has played a lot of tennis. Exhibition tennis, yes, both in friendlies with Roger Federer and earlier this week in Abu Dhabi, where he yet again battled his buddy (and Tomas Berdych). But still tennis nonetheless. For that reason, I expected to see some sign of fatigue from Rafa this week, at an event that doesn't mean much in the big picture.

What I didn't expect was that such a letdown would come against Lukas Lacko, the 23-year-old Slovakian ranked No. 89. It happened in the second set today, after Nadal had just won the opening set in a tiebreaker. Lacko, who can hit a hard ball without much body turn, obviously surprised Nadal in set two; though the world No. 1 won a close first set, he was never uncomfortable. Quickly, Lacko raced to a 4-0 lead, held serve again, then broke Rafa a third time for the shutout. By the end of this lopsided stretch, Nadal looked as if he had a coach flight to catch, spraying a forehand near the stands and dumping a feeble backhand slice into the net. It was the first 0-6 set Nadal suffered since February 2009, when Andy Murray beat him in the Rotterdam final, 6-3, 4-6, 6-0.

The lull was only temporary, though, as Nadal raced to a 4-0, double-break lead of his own once the decisive set began. Lacko made it respectable by getting one of those breaks back, and the final scoreline was a competitive 7-6 (3), 0-6, 6-3. Up next is Ernests Gulbis, who, even if he was the beneficiary of another Nadal misstep, probably couldn't make him pay. But Nadal's likely semifinal opponent, Nikolay Davydenko, likely wouldn't be as generous.

—Ed McGrogan