Big tennis fans (and players), Kate, 30, and Pippa, 28, clapped enthusiastically as Murray took the early lead against Roger Federer, and they were seen sharing a giggle in the royal box above Centre Court.
In the end, though, Federer bested Murray and took home his seventh Wimbledon title, and the sisters stood as Murray gave an emotional speech after his defeat.
Kate's husband William had a prior commitment and couldn't be at the match. Also in the royal box: David and Victoria Beckham. Kate stopped to talk to the L.A.-based pair before taking her seat.
Kate wore a cream jacket from Joseph, which she previously sported at the Epsom Downs racecourse in June 2011. And she teamed it with a Vanessa dress by Joseph, which she donned in Quebec City last summer. She beamed with joy and joined the 15,000 spectators in applause as Murray took the first set.
Kate was last at Wimbledon late last week, watching Murray alongside William, 30.