Beijing, China, 5 October 2017 | Reuters

Nick Kyrgios has a big serve but he may have an even bigger heart.

After firing 11 aces in his 3-6 6-2 6-2 win over Mischa Zverev at the China Open on Wednesday, the Australian world No.19 pledged $50 for every one of them to help victims of hurricane-hit Puerto Rico.

The 22-year-old joined forces with Monica Puig to donate $10 for every ace he hit until the end of the year, but said in a statement that he was raising the amount after reaching the quarterfinals in Beijing.

You know what? I'm upping my offer for @MonicaAce93 #DonateWithMonica to $50 per ace. Let's help Puerto Rico ❤️🙏🏽https://t.co/ydPq2wzUod

— Nicholas Kyrgios (@NickKyrgios) October 4, 2017

Puig initiated fundraising efforts on social media after Hurricane Maria devastated her native Puerto Rico and Kyrgios has been actively championing the cause.

“In light of what’s happened in Puerto Rico and seeing so many good people struggle, I will be helping fellow tennis player Monica Puig in her admirable fund raising efforts to help the great people of Puerto Rico,” Kyrgios said.

The worst to hit the US territory in more than 90 years, Hurricane Maria has killed at least 19 people.

Let's come together to help rebuild, heal and restore the beautiful island that I proudly call home. https://t.co/7idjtL4fZq — 🇵🇷❤️ pic.twitter.com/diKiEEqurG

— Monica Puig (@MonicaAce93) September 20, 2017

In late action on Wednesday third seed Grigor Dimitrov joined Kyrgios in the last eight in Beijing.

He beat former US Open champion Juan Martin del Potro in straight sets to advance to a last-eight showdown with Spain’s fifth seed Roberto Bautista-Agut.

Kyrgios next faces Belgium’s Steve Darcis just weeks after the pair met in the Davis Cup, a clash won in five sets by the Australian.