Pittsburgh Pirates starting pitcher Paul Skenes celebrated girlfriend Olivia Dunne's birthday on Wednesday. The Pirates ace planned the birthday celebration for the former LSU star.In an Instagram post on Wednesday, Skenes shared the decoration for Dunne's birthday celebration. While the post recapped their year together, one of the pictures showed Dunne standing next to a birthday cake made of balloons, holding a bouquet of white roses."Happy Birthday," Skenes captioned the post. View this post on Instagram Instagram PostDunne shared the behind-the-scenes moments from her special day, praising the Pirates ace for the decoration. She also expressed her surprise at watching the decoration for the first time, captioning her video:"Oh my."(Image source - Olivia Dunne Instagram)In another story, the former LSU gymnast was taken aback by cotton candy being part of the decoration."Real cotton candy omg," Dunne wrote highlighting cotton candy inside a balloon.Dunne, who retired from gymnastics after her tenure ended with the LSU Tigers, celebrated her 23rd birthday on Wednesday.Paul Skenes' girlfriend Olivia Dunne's sister, Julz Dunne, shared sneak peek of her birthday celebrationOlivia Dunne's elder sister Julz Dunne shared an Instagram story to gave a sneak peek of her sister's birthday celebration. Julz shared a picture of the cake made by balloons in her story, writing:"Bruh, who put this in my bedroom."(Image source - Julz Dunne Instagram)In her subsequent story, Julz shared a picture of Olivia pretending to eat the entire cake on her own, prompting a reaction from her elder sister."Let them eat cake."(Image source - Julz Dunne Instagram)With her gymnastics career in the books, Dunne is taking on different endeavours. She appeared on the Sports Illustrated cover earlier this year and also walked the runway for the renowned magazine's show.Dunne has also attended many games to cheer for her boyfriend throughout the season after her retirement. She has been in the stands for several of Skenes' starts, cheering him in his pursuit of a maiden National League Cy Young award.