Roger Federer of Switzerland leaves the court after losing to Albert Ramos-Vinolas of Spain during their men's singles match at the Shanghai Masters tennis tournament in Shanghai, China, October 13, 2015. [Photo/Agencies]

World number three and defending champion Roger Federer suffered a surprise defeat in the second round of the Shangahi Masters on Tuesday, losing 7-6(4) 2-6 6-3 to Spain's Albert Ramos-Vinolas.

The Swiss, returning to action after a month off, looked rusty against the 70th-ranked qualifier and despite looking back on track when he cruised through the second set, he succumbed in the decider to a single break of serve.

US Open runner-up Federer, 34, banged down 15 aces and won more points than his opponent but a lack of sharpness at crucial moments sent him spinning to defeat.