Rafael Nadal continued his winning run while Roger Federer returned to action with a victory at the Shanghai Masters.

Federer took on Diego Schwartzman in his first match since losing to Juan Martin del Potro in the quarter-finals of the US Open just over a month ago.

The world number two was not on top form against a tricky opponent but ground out a 7-6 (7/4) 6-4 victory after an hour and 33 minutes and faces Alexandr Dolgopolov in round three.

Federer, who had a first-round bye, told Sky Sports: “It’s hard to play your very best starting a tournament. I knew he was dangerous. Overall I’m very happy, it’s a great first match for me.”

Federer spent 39 minutes longer on court than US Open champion Nadal, who demolished young American Jared Donaldson 6-2 6-1.

Donaldson matched his illustrious rival for four games but after that Nadal, who has never won this title, was at his ruthless best, racking up a 13th consecutive victory.

Third seed Alexander Zverev was on court for just 12 minutes before Aljaz Bedene retired trailing 4-0 with a knee injury but Grigor Dimitrov had a much tougher time against Ryan Harrison.

The sixth seed faced three match points at 3-6 in the deciding tie-break but won five points in a row to triumph 3-6 6-3 7-6 (8/6).

David Goffin’s winning run came to an end, the Shenzhen and Tokyo champion beaten 7-6 (7/4) 6-3 by Gilles Simon, while Kevin Anderson’s hopes of qualifying for the World Tour Finals were dealt another blow with defeat by Jan-Lennard Struff.