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.

Nick Kyrgios has joined Monica Puig's fundraising campaign. Credit:AP

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 quarter-finals in Beijing.

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