World number one Serena Williams will play older sister, Venus, for the ninth time in a grand slam.
The sisters will battle it out in the quarter-finals at the US Open after Serena won against 19th seed Madison Keys in just two sets at Arthur Ashe Stadium on Monday morning (AEST), 6-3 6-3.
Earlier, Venus advanced to the quarter-finals by defeating 152nd-ranked Estonian teen qualifier Anett Kontaveit 6-2 6-1.
In a post-match interview, Serena – who currently leads the sister rivalry – said she still needs to be “ready” for her older sister.
“The only difference to playing Venus now is that we’re a lot older. She’s playing great. I have to really be ready for her. At least one of us will be in the semis,” she said, according to the BBC.
“I don’t feel any pressure [to win the Grand Slam]. Winning four in a row at Wimbledon was amazing. Now I have a chance here to make it five and the New York crowd is pushing me on. It makes me want to to perform and do better.”
Serena, who holds all four major tennis titles, is trying to complete the first calendar Grand Slam since Steffi Graf in 1988 and match Graf’s Open Era record of 22 career Slam singles titles by capturing her Open Era record seventh US Open crown.
But Venus, two years older than Serena at 35, could play spoiler to the history chase as she tries to add to a trophy collection that includes the 2000 and 2001 US Opens and five Wimbledon titles, the most recent in 2008.
“Awesome. It has been awesome,” Venus said when asked about her sibling rivalry.
“I’m so proud of Serena and I think she’s proud of me. We inspire each other.”
Serena leads the sibling rivalry 15-11 but they have split four US Open meetings, including the 2001 and 2002 finals.
The match-ups are usually dominated by Serena, who won their most recent matchup in the fourth round at Wimbledon in July.
The Wimbledon victory that completed her second “Serena Slam” also made her the oldest woman to win a major title at 33.