Roger Federer of Switzerland hits a return during the singles final match against Rafael Nadal of Spain at 2017 ATP Shanghai Masters tennis tournament in Shanghai on Oct 15, 2017. [Photo/Xinhua]

"It's been a pleasure playing against you here today."

Federer, fondly known as "Cow" in China for his laid-back personality, had started the better in grabbing the break before he then rattled through his own service game for 2-0.

Federer, a 19-time Grand Slam champion, was in full flow under the Qizhong Tennis Center roof, which was closed because of downpours in Shanghai.

Nadal, 31, fresh from winning the US Open and China Open in Beijing, groaned through the rallies; Federer, in stark contrast, was all quiet efficiency.

Somewhere in the stadium somebody rattled a cow bell.

Federer rapidly made it 4-2 with two booming aces in a row, drawing huge cheers from the crowd.