New York:
Venus and Serena Williams were together again at Arthur Ashe Stadium on Friday, but injured world number one Serena could only watch as her older sister advanced to the fourth round of the US Open.
US third seed Venus Williams, a seven-time Grand Slam champion, defeated Luxembourg's Mandy Minella 6-2, 6-1 in 74 minutes.
Venus Williams, the last woman to win back-to-back US Open titles from 2000 and 2001, will face Israeli 16th seed Shahar Peer for a quarter-final berth.
Wimbledon and Australian Open champion Serena Williams, the world number one who suffered cuts to her feet that required surgery, was in the stands for the first time during one of her sister's matches this week.
"It was good to see her," Venus Williams said. "Usually we have a tournament together. Not this time. But it was good to have her back."
Venus Williams, like her sister, did not play during the run-up to the US Open because of an injury, with left knee pain keeping Venus idle but not slowing her now.
"So far I have been OK. I'm just looking to take my game to the next level every round," she said.
"It's not easy but I feel like I'm doing a really good job with it. My concern is to be able to make the play and be able to play the best I can."
Venus Williams wore a self-designed black dress with silver fireworks bursts meant to symbolize New York.
"My outfits this year have been based on the cities I have played in," she said. "It's like bursts of fireworks and about a celebration of me playing my best at home and doing what I love and being able to wear something fun."