Serena Williams has paid a heartfelt tribute to close friend Meghan Markle via a post on social media. Williams' post came shortly after Meghan Markle and Prince Harry's interview with Oprah Winfrey was aired in the United States.During the interview, Markle and Harry spoke about their experience within the British royal family after their wedding. They also spoke about their decision to step aside from their royal duties and move to the United States.In the post, Serena Williams described Markle as her 'selfless friend' who 'lives her life and leads by example with empathy and compassion'. Williams further added that Markle 'teaches me every day what it means to be truly noble'.Serena Williams went on to talk about the rampant sexism and racism present in the media and its harmful effects. The 39-year-old ended the note by expressing hope that her daughter, Markle's daughter and all other girls across the world 'live in a society that is driven by respect'.pic.twitter.com/fYx4HlZutl— Serena Williams (@serenawilliams) March 8, 2021Like Meghan Markle, Serena Williams has often talked about the racism that she, her sister Venus Williams and her family have had to face ever since they burst on to tennis scene in the late 1990s.Serena Williams’ history at the BNP Paribas Open in Indian Wells has been well-documented. The American was booed during the 2001 Indian Wells final against Kim Clijsters, with allegedly racist undertones.Considered by many to be the fifth Slam on the tennis calendar, the Williams sisters boycotted the tournament for 14 years before finally returning in 2015.Serena Williams and Meghan Markle have developed a close friendship over the yearsSerena Williams (L) and Alexis Ohanian at the wedding of Prince Harry and Meghan Markle in May 2018A close friendship between a 23-time Grand Slam tennis champion and an American actress of mixed origin who went on to marry into the British royal family, seems like an unfamiliar script. But that's exactly how the relationship between Serena Williams and Meghan Markle has panned out over the years.The pair first met at the 2010 Super Bowl, but it wasn't until their 2014 meeting while playing a flag football event that they truly hit it off. Over time, the two bonded over their interests in fashion, their respective careers, the negative press coverage they both received, their marriages and more recently their children.Serena Williams praised Meghan Markle after she supported her at her #Wimbledon final: "She's such a great friend and a great person as well, and always positive, no matter what. It's so good to have people like that just to know." https://t.co/lo061awJu9 pic.twitter.com/PX62OhIndK— E! News (@enews) July 13, 2019Serena Williams and husband Alexis Ohanian even traveled to Britain to attend the Meghan Markle-Prince Harry wedding in 2018..@serenawilliams looked suitably royal for today's Royal Wedding between Prince Harry and Meghan Markle!#USOpen📷: @serenawilliams pic.twitter.com/bpuuYzaHTD— US Open Tennis (@usopen) May 19, 2018A year later, Markle traveled to cheer Williams on at the 2019 US Open, just a few months after giving birth to her first born.ROYAL FAN: Meghan Markle, Duchess of Sussex, cheers on close friend Serena Williams at the U.S. Open, after taking a last-minute flight from London, with Williams vying for a record-tying 24th Grand Slam title. https://t.co/zsbtT4Ekp9 pic.twitter.com/iaY4q2WOql— World News Tonight (@ABCWorldNews) September 7, 2019