Mary Carillo says Maria Sharapova's "biggest mistake" was beating Serena Williams in 2004 Wimbledon final, feels Serena has still not gotten over the loss

In the latest episode of "The GOAT: Serena" podcast, former players Chanda Rubin and Zina Garrison spoke to Mary Carillo and Patrick Mouratoglou about Serena Williams' biggest rivals and some of the American's career highlights.

Carillo, a former World No. 33, discussed the 2004 Wimbledon final, which saw a 17-year-old Maria Sharapova deny Serena Williams a third consecutive title at the All England Club.

The 64-year-old described Sharapova's feat as the "biggest mistake" made by the Russian and went as far as to claim that Williams still hasn't fully come to terms with the loss.

"The worst thing Maria Sharapova could have done was to win Wimbledon at age 17 against that woman who was trying to win her third straight," Mary Carillo said. "That was Maria's biggest mistake. At the time she had no pressure, had great poise and was going for her shots. I don't think Serena has still gotten over it."

Sharapova's only other victory over Williams came later that season at the year-end championships. The duo have met 22 times over the course of their careers, with Williams staying undefeated against the Russian post 2004.

Carillo believes their one-sided rivalry attracted attention due to Sharapova's beauty and demeanor.

"And then she (Sharapova) beat her (Williams) at the year-end championships and that was it. That rivalry was big because Maria Sharapova was big. She was beautiful, she had contracts, there was an arrogance to her. She was a legit World No.1, later in her career she even won a couple of French Opens," she added.

Serena Williams at the London Olympics

Serena Williams' long-time coach Patrick Mouratoglou also appeared on the podcast. The Frenchman reminisced about the 2012 London Olympics, where Serena Williams pulled off a commanding 6-0, 6-1 victory over Maria Sharapova in the gold-medal match.

Mouratoglou reckons Williams played some of the "best tennis of her career" at the tournament. He went on to add that the American derived a lot of confidence from her Wimbledon triumph just a few weeks before the Games.

"The 2012 Olympics was where she played some of the best tennis of her career; she crushed everybody," Patrick Mouratoglou said. "At Roland Garros she got out in the first round but she won Wimbledon and that gave her a lot of confidence. It paid off at the Olympics where she was untouchable. The best match was the final against Sharapova."

"The level of play was great every time"- Patrick Mouratoglou on the Serena Williams-Victoria Azarenka rivalry

Victoria Azarenka and Serena Williams at the 2012 US Open

During the podcast, Patrick Mouratoglou also highlighted that the time between 2012 and 2015 was the most dominant period of Serena Williams' career. The American won eight Grand Slam titles across four seasons and finished years 2013-15 atop the world rankings.

Mouratoglou proceeded to name Victoria Azarenka as Williams' "toughest rival" during that period. Williams and Azarenka have met 23 times in total, and the American enjoys a 18-5 lead in the head-to-head.

Mouratoglou believes the two pushed each other to become better players.

"I think the period between 2012 and 2015 had the best years of Serena's career because she won eight Grand Slams and stayed No. 1 for three-and-a-half years," Mouratoglou said.

"I think her toughest rival was Azarenka. Even though Serena beat her most of the time in the Majors, the matches were always super close. Vika beat her several times in Masters and other tournaments and was able to bring her best tennis every time. I think they were both pushing each other and the level of play was great every time," he added.