By DANIELLA MATAR Associated Press MILAN (AP) -- The Williams sisters want to defend their Olympic doubles title in London next summer. Serena Williams said that she and sister Venus are eager to go for their third Olympic gold together after victories at the 2000 Sydney and 2008 Beijing Games. "We're the defending champion and we want to defend our title and I don't see why we wouldn't," Serena said of the London Games. "This is a good preview to the Olympics, we both want to play. So this is a great, great time for us, so exciting." The sisters were unable to defend their title in Athens 2004 after Serena injured her knee. Venus also won the singles gold medal in Sydney. However, the five-time Wimbledon champion's ranking has fallen to No. 104 because of injuries, while Serena's ranking has improved to 12th after missing nearly a year with injuries and health issues. Venus has played just once since pulling out of the US Open three months ago because of an immune system disease. She defeated Serena 6-4, 7-6 (5) in an exhibition match in Colombia last week. Venus has changed her diet to include more vegetables after being diagnosed with Sjogren's syndrome, which can cause fatigue and joint pain. "I'm eating different things and that's helping." Venus said. "I need to try and be stronger for next year. This is a good start for me. It'll show me where I'm at physically. "The goal is to come back in Australia. I'm taking each day at a time. When I feel good, I feel really happy. Today I feel really good, so it's a great day." Serena returned shortly before Wimbledon after dealing with foot surgeries and blood clots in her lungs. She fell to No. 175 but has managed to rise in the rankings. "I told myself I wanted to end the year in the Top 20," Serena said. "But I didn't think I would. So I'm really happy now." Serena has played just once since losing to Samantha Stosur in the US Open final in September. "I was tired after the Open and didn't want to go to Asia," she said before bursting into laughter and correcting herself. "Well no, I was injured." The Williams sisters, who often design their own tennis outfits and have launched clothing lines, said they've been to Armani during their stay.