Roger Federer hailed old rival Rafael Nadal as "super-inspiring" after the world No 1 joined in the clean-up operation in Majorca.
Flash floods have killed 12 people on the island where Nadal lives and the tennis star was pictured wearing boots and white gloves, mopping up the floor of a warehouse, on Wednesday.
The 17-time Grand Slam champion, currently sidelined through injury, has also offered to open up his sports centre and tennis academy to people made homeless by the floods.
"I know how important Majorca is to Rafa and I have been in touch with him to see if I can help with anything," Federer said in a video message recorded in Shanghai, where he is currently competing.
"I have seen him helping in the village where he comes from and to see that is super-inspiring. Rafa, you have our support.
"We are thinking of all the people in Majorca. We wish you strength in these difficult times and I hope to be back on Majorca soon."
Fellow rival Novak Djokovic, also taking part in Shanghai, said he hoped Nadal's efforts would inspire others.
"A big hug and friendly regards to Rafa and well done amigo for helping out," the reigning Wimbledon and US Open champion said.
"I invite anyone to give their support in any way they can. Gracias."
Watch live continued coverage of the Shanghai Masters quarter-finals on Sky Sports Action from 6am on Friday.
We have every major tennis event covered from all angles via our website skysports.com/tennis. On the move? Head to our app for mobile devices and iPad, or follow our Twitter account @SkySportsTennis to join in the conversation.
We will have coverage of the ATP Finals at London's O2 in November with every match live on Sky Sports.