Muguruza said that she shed tears upon hearing the news about the six-time US Open champion and 23-time Grand Slam winner Williams' "evolving away from tennis."
Two-time Major winner Muguruza added that "having zero options to become a tennis player," her mom encouraged her by making Serena Williams and her older sister Venus Williams her inspiration.
"I really cried when I saw the news because she inspired many of us. I'm one of those girls that started in a very difficult sport, playing tennis, having zero options to become a tennis player. And I remember my mom always saying, 'Look at these sisters and they made it. Look how fearless they are. You have to be like them," said Muguruza, adding, "And, well, thanks to her, I became the player I am."
Gauff, meanwhile, equated Williams to the sport of tennis itself, emphasizing how she changed the game.
"Serena is definitely tennis, I would say. The way that she's changed the game. If you look at from when she started her career and how people are playing, to now when she's ending it and how people are playing. I think that massive change is due to her. No one was doing it like her and I dont think anyone will ever do it like her," said Gauff.
Ons Jabeur, Serena Williams' doubles partner in Eastbourne, and Madison Keys also shared good words about Serena.
Like Muguruza, Jabeur and Keys drew inspiration from the 40-year-old Williams as they carved their own paths in tennis.
"Serena really created history for tennis and opened the doors for us. For me, as a young girl dreaming to play tennis, she's such an inspiration. And I was lucky enough to be the same on tour with her," said Jabeur.
"She's been an absolute inspiration for me ever since I was little. I grew up watching her. And then being able to play her has been some of the greatest moments of my life and my career and something I'll always remember and cherish," said Keys.
Garbine Muguruza, Coco Gauff, Ons Jabeur and Madison Keys join Serena Williams in US Open third round
Serena Williams is still in the thick of the US Open battle as she made it to the third round after beating World No. 2 Anett Kontaveit in three sets. Garbine Muguruza, Coco Gauff, Ons Jabeur and Madison Keys joined her there as they also got past their respective second-round opponents.
Williams will next face Ajla Tomljanovic in what is expected to be another packed Arthur Ashe Stadium.
Meanwhile, Muguruza and Petra Kvitova will face each other in a fight between two Grand Slam champions, while Gauff meets Keys in an all-American battle. Another American, Shelby Rogers, squares off with Ons Jabeur.