When Serena Williams took on Ana Ivanovic in the opening match of the BNP Paribas WTA Finals Singapore on Monday night, Caroline Wozniacki - due to compete the next day - showed up court-side in support of her good friend.
So when Wozniacki upset Russia's Maria Sharapova in an epic three-hour-plus battle on Tuesday, it seemed only natural that a congratulatory tweet from Williams came mere minutes after the Dane's victory.
Meanwhile, even Li Na could not help but admit that she hopes Petra Kvitova will win the WTA title this week, because "under the table, we're very good friends".
Recalling her retirement ceremony last month in Beijing, she acknowledged to The Straits Times that it was the Czech player's moving speech that brought her to tears.
Friendship between top players has been one of the more endearing themes of the women's tour this year, perhaps most seen in how Williams stood by Wozniacki after the Dane's fiance, golf star Rory McIlroy, broke off their engagement.
But until very recently, camaraderie was not one of the more recognisable traits of the women's professional tennis tour.
In fact, it was just last year that Williams and Sharapova were quoted as taking swipes at each other's romantic relationships.
There was also signs of bad blood between Williams and fellow American Sloane Stephens after their clash at the Australian Open last year.
For years, it had seemed that, when it comes to the women's game, gone were the days when rivals like Martina Navratilova and Chris Evert could practise together just before vying each other for a Grand Slam title.
However, Wozniacki believes that friendship on tour has always been existent - just not under the public eye.
"We're very friendly on tour," she said. "We travel to the same tournaments and we see each other every week. Obviously we compete against one another on the court, but off the court we just have a laugh and enjoy one another's company."
Still, there are players like Canada's Eugenie Bouchard who prefer to keep those closest to their hearts off the tennis court.
She said: "I'm friendly with all the players... I just wouldn't say I have true best friends on the tour. I like to keep those outside of tennis, so we don't talk about tennis all day. We talk about more important things, like boys," she joked.
In a 2010 ESPN documentary on the lifelong friendship between Navratilova and Evert, the legends spoke about their unique relationship that has spanned three decades and stood the test of 80 matches, including 16 Major finals.
While admitting that they did not always get along, Navratilova said it was rare having a confidante who fully understood what life as a professional tennis player was like.
"Going through the same things to get to the same point in your life... all that brings an honesty, a trust that I don't have with anybody else," she said.
So while she has never been inclined to keeping close friends on tour, Williams admits her perspective has changed as she matured.
She said: "It's definitely something that's come about when I'm older. Life is far too short and there are so many things that are so much more important in life than hitting a tennis ball.
"Things do last longer than tennis. I think if you do have a good friendship, even if it's one, it's worth it."