More than seven years after her last Grand Slam title match, Venus Williams would be forgiven for being a little nervous when she stepped inside Rod Laver Arena to face her sister, Serena, for the Australian Open championship. It was Venus who was smiling during warm-ups and looked far looser at the start of Saturday’s match – not her sister, the 22-time major winner, who double-faulted three times in a single game to drop serve.