Venus Williams stepped on court for her opening-round match against Karolina Muchova at Arthur Ashe Stadium on Monday, August 25. Serena Williams expressed her pride at her sister's return to the hardcourt major with a touching message online despite the latter's opening-round exit.It has been two years since Venus Williams' previous Grand Slam outing and 28 years since she made her debut at the US Open. Through the years, she has battled Sjögren's syndrome, an autoimmune disorder, and uterine fibroids, along with injuries that unfortunately come with competing as a professional athlete. Venus, 45, is now the oldest singles player at the US Open since 47-year-old Renee Richards in 1981.Serena Williams shared her sentiments on her sister's return to court via Instagram. She used heart-on-fire and white-heart emojis and wrote:"I am immensely proud of you @venuswilliams"Screengrab from Serena Williams' Instagram @serenawilliamsVenus Williams was welcomed on court with thunderous applause. Her fiancé, Andrea Peti, was cheering her on in her player's box. The couple confirmed their engagement at the Cincinnati Masters this year and have yet to announce a wedding date.Serena Williams gave relationship advice to her older sister Venus Williams ahead of her wedding to fiancé Andrea PetiSerena Williams(left) and Venus Williams(right). Image: GettySerena Williams had some advice to give Venus Williams before the latter tied the knot with her fiancé, Andrea Peti. He is an Italian actor and model, and the wedding is anticipated in Peti's home country in September.In a short clip on Instagram, the 23-time Grand Slam champion could be seen on the Today show that aired on August 24. Considering that she has been married for eight years and is a mother of two, the host asked her what relationship advice she would give to Venus. Serena, who is married to Reddit co-founder Alexis Ohanian, replied:"My advice is to just always have fun, you know, to always go on dates, and to just take a moment and just, like, dance. Dance and let your guard down, just let you feel vulnerable. You just have these different moments. I'm no expert, like, I definitely am not perfect. I mean, I'm close (laughs)." View this post on Instagram Instagram PostSerena Williams is focusing on her family since she hung up her racket at the 2022 US Open. She often shares snippets from her life at home with her daughters via social media. Her daughters, Olympia and Adira, also have their respective Instagram handles operated by their parents.