Rafael Nadal's Loss to Novak Djokovic at Sony Open Is Cause for Concern

It's not time for a full-blown panic attack, but Rafael Nadal's torrid defeat at the hands of Novak Djokovic at the Sony Open is something to closely monitor. Yes, the tournament at Crandon Park routinely acts as a thorn in Nadal's side. He's now finished as the runner-up four times in Miami. Still, it's not a make-or-break tournament for the Spaniard, who typically ups the ante at Grand Slams.  But this time was different. It wasn't just that Nadal lost. It's how he lost.  The 6-3, 6-3 defe...