WORLD No. 1 Serena Williams stayed on course for the first calendar Grand Slam since 1988, advancing to the U.S. Open semifinals by defeating older sister Venus Williams 6-2, 1-6, 6-3.

    A smiling Venus wrapped both arms around her little sister for a warm hug at the net and whispered, “So happy for you.”

    “Obviously we are very, very tough competitors on the court,” Serena said later, “but once the match is over, the second it’s done, you know, we’re sisters, we’re roommates, and we’re all that.”

    Serena called their unique sibling rivalry “the greatest story in tennis.”

    With two more match wins, Serena would become the first player since Steffi Graf in 1988 to collect all four Grand Slam titles in a single season. Plus, if she can win what would be her fourth U.S. Open in a row, and seventh overall, she would equal Graf with 22 major championships, the most in the professional era and second-most ever behind Margaret Court’s 24.

    “That would be huge, not just for me, but for my family, just for what it represents and how hard we have worked and where we come from. So it would be a moment for our family,” said the 23rd-seeded Venus, who is 15 months older. “But at the same time, if it doesn’t happen it’s not going to make or break you. We don’t have anything to prove. She has nothing to prove. She’s really the best ever.”

    Serena is 16-11 in their all-in-the-family matches, including 9-5 in majors and 3-2 at the U.S. Open. And 14 years to the day after Venus beat Serena in the 2001 final at Flushing Meadows, they met again with so much at stake.

    Well-known folks such as Donald Trump — who was booed when shown on video screens — Oprah Winfrey and Kim Kardashian dotted the teeming stands in Arthur Ashe Stadium, and the sellout crowd of 23,771 got its money’s worth.

    “They both played their best,” said Serena’s coach, Patrick Mouratoglou. “If they were feeling uncomfortable with playing each other, they could not play at that level.”

    The sisters combined for 57 winners (Serena had more, 35) and only 37 unforced errors (Venus had fewer, 15).

    Serena next faces unseeded Robert Vinci of Italy, who reached her first Grand Slam semifinal at age 32 by outlasting Kristina Mladenovic 6-3, 5-7, 6-4.

    (SD-Agencies)