Serena Williams is summer ready!

The 35-year-old tennis star shared a sexy bikini photo on Instagram ​on Friday. Her reason?​​ "Just because."
The snap features Williams posing in a slinky yellow two-piece while showing off her rock​-​hard abs and amazing biceps.

Williams may be flaunting her bikini ​bod​, but she'll be rocking a more formal look for her upcoming wedding to Reddit co-founder Alex Ohanian. The couple announced their engagement in December with Williams sharing a heartfelt post on her Reddit account. 

"I came home. A little late. Someone had a bag packed for me. And a carriage waited. Destination: Rome,"she wrote at the time. "To escort me to my very own 'charming.' Back to where our stars first collided. And now it was full circle. At the same table we first met by chance, but by choice. 

"Down on one knee. He said 4 words. And I said yes," Williams added.​