Serena Williams has gushed over her sister Venus Williams after watching her sibling get married

Serena wrote on Instagram: "My sister's keeper. Venus, where do I even begin? From the backyard courts to the biggest stages in the world, you've always led with grace, strength, and a heart bigger than any trophy. Watching you step into this next chapter surrounded by love felt like watching the sun rise...steady, powerful, and full of promise.

"You've been my built-in best friend, my protector, my teacher, and my reminder to always walk in purpose. Seeing you this happy, this loved, this radiant... it means everything to me."

Serena also admitted she "couldn't be prouder" to stand alongside Venus at her wedding, which took place in Florida earlier this month after an initial ceremony in Andrea's native Italy.

She added: "To love, to partnership, to laughter, and to a lifetime of choosing each other every single day. I couldn't be prouder to stand beside you, not just today, but always."

In September, Serena told how she was helping Venus plan her wedding, because she is someone who "gets things done".

She said to PEOPLE: "We talk every day now because we have so much going on. Well, let me rephrase that. Venus has so much planning that she's doing that I'm just talking to her all the time.

"She wanted me to help her with some dresses, or was it hairstyles?

"She wanted literally 14 hairstyles - and she was like, 'What do you think'?

"So she sent me her options and within 30 minutes I had them not only done, but in a PDF file what hairstyle looked best on everyone."