World No. 2 Roger Federer barreled into the third round of ATP Shanghai Masters on Wednesday, beating Russia's Daniil Medvedev in a nail-biting 6-4, 4-6, 6-4 in his opening match of the tournament.

"It was a great first round for me against a guy who has been playing excellent. I was impressed by how he played," said the defending champion, who has never played Medvedev before.

The 20-time Grand Slam winning Swiss earned the first break at the outset of the match and completed the first set in 34 minutes. But Medvedev, the newly-crowned Japan Open champion, bounced back in the second set with strong hold of serve and a decisive break to make it 6-4.

In the decider, Federer broke in the ninth game after a Medvedev shot long and then closed out the match in one hour and 53 minutes with an ace. 

The 37-year-old top seed will next play Spain's Roberto Bautista Agut on Thursday in the last 16 to chase his third title in the ATP 1000 showpiece.

Wu Yibing lose to Kei Nishikori

China's wild card entry Wu Yibing was defeated by eighth-seeded Japanese Kei Nishikori 3-6, 6-0, 6-3 in one hour and 40 minutes.

The 18-year-old Chinese young talent stunned the former World No. 4 in the first set with superior shots and returning to make it 6-3. But Nishikori was back on track in the second set and dominated the rest of the match to reach the next round.

"I was not able to do anything in the first set, he was playing top 50, top 30 tennis," Nishikori spoke highly of his opponent. "I thought about losing the match maybe, so I was happy with my tennis in the end."

Earlier in the day, the third seeded Del Potro, who lost the final of China Open last week, overcame Richard Gasquet of France 7-5, 7-6(7). The 30-year-old Argentine trailed twice but fought from behind to conclude the match with an ace in the tie-break of second set.

World No. 5 Alexander Zverev saw off Nicoloz Basilashvili 7-5, 6-4.