Serena, 30, and Venus, two years older, have won 10 of the last 13 singles titles at the All England Club.
The last of Venus’s 43 career titles came in Dubai in 2010 while her last Grand Slam title was in 2008, she was diagnosed with the fatigue-related illness Sjogren’s Syndrome last year which kept her off tour from the US Open until the Miami tournament in March this year.
Many in the sport expect Venus, now down at 58 in the world, to quit after this year’s US Open and having had another shot at the Olympics, which will be held at Wimbledon.
“I don’t know what I would have if Venus didn’t exist. I don’t even know if I would own a Grand Slam title or if I would play tennis, because we do everything together,” said Serena.