And look how happy they are!
Frida, Mel, Isabelle and Costela were rescued from slums by the Association of Animal Wellbeing and trained to fetch the tennis balls for the players.
"We want to show that abandoned dogs can be adopted and trained," said Andrea Beckert, a trainer from the Association of Animal Wellbeing.
"After all, it’s not easy to get a dog to only pick up the lost balls, and then to give them up!"
The four dogs proved a delight for the crowd watching as they cheered on their efforts. And the dogs are expected to participate in the award’s ceremony on Sunday.