He has been bemoaned as the bad boy of tennis but Nick Kyrgios demonstrated his generous side in pledging $50 for storm-hit Puerto Rico each time he blasts an ace.

The 22-year-old Australian initially said he would give $10 for each ace towards emergency relief on the US island following Hurricane Maria, which hit two weeks ago leaving more than 30 people dead and thousands homeless.

But in a tweet Kyrgios subsequently wrote: "You know what? I'm upping my offer... to $50 per ace. Let's help Puerto Rico."

Kyrgios, the talented but sometimes troubled world number 19, sent down 11 aces in beating Germany's Mischa Zverev at the China Open on Wednesday and will meet the Belgian Steve Darcis in the quarter-finals.

Monica Puig, the 68th-ranked player from Puerto Rico, is drumming up support from the tennis community to help.

Former number one Maria Sharapova, dumped out of Beijing on Wednesday by Simona Halep, plans to travel to the stricken US territory with Puig to do her bit.

"When you're not there, you know how much people are suffering, but you don't really feel it", said the Russian.

President Donald Trump has asked Congress for a bumper $29 billion package of emergency relief for Puerto Rico.

Source: AFP