Djokovic is seeded first in the tournament but the seedings were determined before Rafael Nadal passed Djokovic in the rankings and retook the top spot with a win in the semifinals of the China Open.
Djokovic answered with a straight-set win over Nadal in the China Open final Sunday and opened his defense of the Shanghai Masters with a 6-2, 6-0 win Wednesday over Marcel Granollers. Djokovic began the match with a break and won the last nine games in breezing into the third round in 70 minutes.
Nadal needed 11 fewer minutes to dispatch Alexandr Dolgopolov 6-3, 6-2 in his second-round match. Nadal lost only 11 points in his nine games serving.
Second-round upsets went to Carlos Berlocq, who stopped 14th-seeded John Isner 6-4, 7-6 (7-4), and Fabio Fognini, who advanced when 16th-seeded Tommy Robredo retired in the second set with Fognini up 7-6 (7-3), 2-1. Fognini draws Djokovic and Berlocq takes on Nadal in the third round.
No. 3-seeded David Ferrer dumped Lukas Rosol 6-3, 6-4 while fourth seeded Tomas Berdych was a 7-6 (7-5), 6-2 winner over Feliciano Lopez and No. 5-seeded Roger Federer took out Andreas Seppi 6-4, 6-3.
Juan Martin del Potro, the sixth seed, got past Philipp Kohlschreiber 3-6, 6-3, 7-6 (7-4) and No. 7 Jo-Wilfried Tsonga topped Pablo Andujar 6-3, 6-2 while eighth-seeded Stanislas Wawrinka was a 6-4, 3-6, 7-6 (7-5) winner over Kevin Anderson. No. 10-seeded Milos Raonic capped the second round with a 7-6 (7-1), 3-6, 6-3 win over Fernando Verdasco.