Novak Djokovic overcomes foot scare to win in Shanghai

Defending champion Novak Djokovic shrugged off a foot injury to ease into the third round of the Shanghai Masters on Wednesday as Argentina's in-form Juan Martin del Potro survived a major scare.

Top seed Djokovic cantered through the first set against Spain's Marcel Granollers 6-2 but early in the second set pulled up in obvious discomfort and called for the ATP trainer, who applied heavy taping to his right foot and ankle.

Despite the medical treatment, the 26-year-old, dislodged this week from the number one ranking by Rafael Nadal, did not look inconvenienced as he returned to the court to seal the second set 6-0. He hit a total of 26 winners.

Earlier, German world number 23 Philipp Kohlschreiber rattled a feverish Del Potro, striking 50 winners and 22 aces in a brave display of attacking tennis that had the Argentine searching for answers before he dug deep to win 3-6, 6-3, 7-6 (7/4).

Kohlschreiber was quickly out of the blocks, unveiling his full repertoire of shots including an impressive single-handed backhand, and breaking at the first opportunity, which proved enough to take the opening set.

Sixth seed Del Potro, fresh from winning his third title of the year at the Japan Open, levelled the second set courtesy of a single break.

The former US Open champion looked set for victory when he repeated the feat in the seventh game of the decider but Kohlschreiber broke back, taking the match into the decisive tie-break.

Del Potro, 25, said afterwards that he felt feverish, admitting he was lucky his opponent made errors at key moments in the tie-break.

"Last night I couldn't sleep really well," said the Argentine. "This morning I took ibuprofen, a couple of pills, trying to help me feeling better. But I'm not 100 percent yet."

"I think my serve helped me a lot to keep playing for the three sets because I made many aces," he added. "With my serve I didn't run too much. I was lucky in the tie-break because he made a few mistakes with his backhand. I won a really tough match."

In other matches, fourth seed Tomas Berdych of the Czech Republic beat Spain's Feliciano Lopez 7-6 (7/5), 6-2 and seventh seed Jo-Wilfried Tsonga eased past Spain's Pablo Andujar 6-3, 6-2.

Veteran Tommy Haas put out fellow German Daniel Brands 6-4, 6-4 but America's top player John Isner lost 6-4, 7-6 (7/4) to Argentina's Carlos Berlocq.

Spain's Tommy Robredo retired from his match against Italy's Fabio Fognini with a wrist injury when trailing by a set.

Drenching rains earlier in the week as a result of Typhoon Fitow forced matches indoors, but the wet weather relented on Wednesday, allowing tournament chiefs to open the roof of the stadium court.