Djokovic Reaches Miami Tennis Open Quarterfinals

Novak Djokovic rolled his eyes after a backhand found the net, shrugged after an early barrage of errors, double-faulted eight times and even heard the crowd at times pulling for his opponent.

None of it mattered. Even when not at his sharpest, Djokovic is nearly impossible to beat.

Looking for his fifth title on Key Biscayne in six years, Djokovic reached the Miami Open quarterfinals Tuesday with a 6-3, 6-4 win over 14th-seeded Dominic Thiem of Austria. Djokovic will meet seventh-seeded Tomas Berdych, who grinded out a three-set win over 10th-seeded Richard Gasquet of France.

"It was far from easy," Djokovic said. "I struggled a lot."

Djokovic, the world's top-ranked player, moved to 25-1 on the year and 27-1 in his last 28 matches on Key Biscayne. He also moved a step closer to becoming the tournament's first back-to-back-to-back winner since Andre Agassi,who won in 2001, 2002 and 2003. Djokovic fended off 14 of the 15 break points he faced and hasn't dropped a set so far in the tournament.