I have always looked up to you and admired you: Serena Williams to Roger Federer

Penning a note for Roger Federer following his retirement from tennis, Serena Williams wrote on Instagram, "I have always looked up to you and admired you." She added, "You inspired countless millions and millions of people, including me, and we will never forget." She further wrote, "Welcome to the retirement club. And thank you for being you @rogerfederer."