Venus and Serena Williams at the 2015 US Open
Credit: AP Photo/Julio Cortez

Talk about a match for the books. On Tuesday night, Serena and Venus Williams took the court at Arthur Ashe Stadium in New York City, where they duked it out in the U.S. Open quarterfinals. And in less than two hours, younger sister Serena came out as the victor, advancing to the semifinals and continuing on her road to tie Steffi Graf with the most Grand Slam titles.

Following the match, which was attended by celebs like Kim Kardashian, Kendall Jenner, Gigi Hadid, Joe Jonas, and Oprah Winfrey, Serena spoke to her big sister's strength's during an on-court interview. "It’s a really great moment. She’s the toughest person I’ve ever played in my life and the best person I know," she said, adding, "It was really difficult today."

Venus only had good things to say about Serena following the match as well. "I'm still very excited to see Serena have an opportunity to win the four majors," she said. "That would be a huge [moment], not just for me, but for my family just for what it represents and how hard we have worked and where we come from." Serena now advances to the semifinals, where she will take on Roberta Vinci.