Arriving on court to the sound of the song "Who Let the Dogs Out", the canines drew cheers and applause from the audience as they helped retrieve stray balls in a doubles match between players Mansour Bahrami, Juan Carlos Ferrero, Henri Leconte and Mikael Pernfors.
Hattie, Tina and Melvin were provided for the event by the charity Canine Partners, which trains dogs to help people with disabilities, and had to learn new skills for the job.
"Normally they're used to picking things up within the job that we use them for, so we may drop pens and inhalers and they're used to retrieving things for us, but we don't generally use an awful lot of tennis balls," Canine Partners Aftercare Manager Claire Anthony said.
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"We've been going to lots of tennis courts and working around self-control around people playing tennis and then retrieving balls and towels."
Former British number one Tim Henman helped train the dogs for the Dec. 6-9 tournament, which is held annually at London's Royal Albert Hall with plenty of the sport's veteran players taking to the court.
"What do they say about working with animals and children? Don't do it," Henman joked at a news conference beforehand.
"Ball dogs" are not new in tennis, with some canines having already appeared on court at the Brazil Open.
(Reporting by Reuters Television; Editing by Marie-Louise Gumuchian)
