Who said you can't teach an old dog new tricks? An exhibition tennis game at the Brazil Open last week between Roberto Carballes Baena and Gastao Elias saw the conventional "ball boys" in tennis, being replaced by "ball dogs".

Four stray dogs, rescued from the streets of Sao Paulo, dutifully played the role of ball boys as they collected the stray balls. Of course, anyone who has played "fetch" with a dog will know how difficult it is to get the dog to drop whatever it is carrying, but with a little encouragement, the dogs eventually returned the balls they carried, much to the delight of spectators.

These dogs were trained by the Association of Animal Wellbeing, specifically to raise awareness about the adoption of strays. "We want to show that abandoned dogs can be adopted and trained," said their trainer.