"Seeing you this happy, this loved, this radiant... it means everything to me" - Serena Williams in full praise of sister Venus after watching her get married

Serena Williams has been in awe of her sister, Venus Williams, after she witnessed her sister get married to actor Andrea Preti.

While they were huge competitors off the court, they are very close and supportive off it, with Serena standing closely by Venus' side at the big day. An initial ceremony occurred in Preti's native Italy in September before following with a five-day wedding in Palm Beach with all kinds of celebrations, from parties to bridal showers to a ceremony in court before the nuptials.

She went to Instagram to state her thoughts on her big sister. "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," she wrote. "Watching you step into this next chapter surrounded by love felt like watching the sun rise...steady, powerful, and full of promise."

The American continued to praise the seven-time Grand Slam champion, with her happiness meaning so much to her. "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."

"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."

Williams described herself as someone who 'gets things done' and that the duo were talking basically everyday with the wedding fast approaching with so much stuff to plan out.

"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 told PEOPLE. "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."

The pair have always been their for each other despite their vicious on court rivalry, seeing them regularly face off against each other. They met in a stunning nine Grand Slam finals together, It was Serena who was the more dominant in these, defeating her in seven of these nine clashes. This included four consecutive matchups between 2002 and 2003. The longevity of the pair can be shown by their final Grand Slam final coming all the way in 2017. It was also famous with the fact that Serena won the title while eight weeks pregnant with her first child.

When at the same side of the court, they were dominant. They won 14 Grand Slam titles together, three Olympic gold medals and in total 22 WTA Tour titles, showing their chemistry on and off the court.

There was a brief glimpse of hope that they could once again step onto the court together. However, after doing the necessary paperwork for a return to tennis, she adamantly halted those rumours of her return. It is the opposite for Venus, who is raring to go ahead of a successful return to tennis at the North American hardcourt swing. She will be playing in the ASB Classic from January 5-11, with a return to the Australian Open possibly on the cards.