After Serena Williams beat her older sister at the U.S. Open on Tuesday, she called her “the toughest player I’ve ever played in my life and the best person I know.“

In an Instagram post on Wednesday, the No. 1 women’s tennis player in the world went one step further.

“She has my heart,” Serena said of Venus. “Memories make my heart filled with more joy than I can express. A lifetime with@venuswilliams will not be enough.”

The match was the 27th between the two sisters in their careers. Serena now leads the series 16-11 and is two wins away from becoming the first tennis player, male or female, to win all four major annual tennis tournaments in the same year since 1988.

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