WATCH: Serena Williams champions inner confidence for women

Williams has won more titles (with 23 Grand Slam singles titles to her name) than any other woman or man during the open era.

"Women need to be celebrated, and they need to embrace what you look like and not from the outside, but from the inside,' Serena said.

"So every time I step out there and that swimsuit, I'm really feeling myself from the inside."