‘Champion. Legend’: Oprah, LeBron and Michelle Obama hail Serena Williams’ career

• 23-time major champion played probable career farewell
• Athletes and friends pay tribute to tennis star's achievements

What is likely to be the final match of Serena Williams's glittering career was played out in front of a crowd packed with celebrities, from Spike Lee to her sister Venus. But for those who couldn't get tickets to Arthur Ashe Stadium on Friday night, there was always Twitter.

Another athlete who can claim to be the greatest in their chosen sport's history was one of the first to congratulate Williams.