"She did it! @serenawilliams ! #bravo #friends #usopen," Markle tweeted after Williams won the 2014 US Open.
Markle shared more about their friendship on The Tig: "She quickly became a confidante I would text when I was traveling, the friend I would rally around for her tennis matches, and the down-to-earth chick I was able to grab lunch with just a couple weeks ago in Toronto."
She added, "We are both the same age, have a penchant for hot sauces, and adore fashion, but what connects us more than those things is perhaps our belief in exceeding expectations — our endless ambition."