Tiger Woods, Michelle Obama Lead Tribute To The "Greatest" Serena Williams
Tiger Woods and former first lady Michelle Obama hailed Serena Williams as "the greatest" on Friday as the tennis superstar headed into retirement. Williams, the winner of 23 Grand Slam titles, played what was almost certainly the last match of her 27-year career at the US Open when she slipped to a three-set defeat to Ajla Tomljanovic.