Remarkably, the American tennis star has been set a target of 30 career singles grand slams.
"I know people are going to be very much focused on the 23rd (grand slam), I'm more focused on the 30th," Patrick Mouratoglou, who has been coaching Williams since 2012, told CNN at the unveiling of his new tennis academy on the French Riviera.
"Why not set up a record that will never be beaten in history?" he asked. "I think she can do it."
Having lost her No. 1 ranking with this month's semifinal defeat at the US Open after a record-equaling 186-week reign, Williams is looking at the long term rather than seeking to overhaul Angelique Kerber and end the year in top spot for the fourth year in a row.
"We're not going to run after that because it would be a bad idea," Mouratoglou said.
Instead, Williams' formidable tennis legacy will be far greater served by eclipsing Margaret Court's record of 24 grand slam singles titles, he added. She is tied with Steffi Graf for second place at 22, the most in the Open Era of professional tennis.
"We decided to let go that No. 1 spot for the moment. Maybe she'll get it back but we shouldn't focus on that -- we focus on the grand slams," Mouratoglou added.
'A very bad season'
With Serena also telling CNN at the academy launch she is "tired of playing unhealthy," it raises the possibility that she could skip the WTA Tour's Asian swing and season finale in order to recover from her injuries -- as she did last year -- but her website schedule
does have her down for three more events this year.
"The good idea with Serena is to organize everything so she has the best chances to win as many grand slams as she can," Mouratoglou explained.
"That's the only goal. If we try to follow too many goals at the same time, we might fail everywhere, so let's focus on the most important."
Williams has suffered what Mouratoglou calls "a very bad season," despite claiming her seventh Wimbledon title in July.
The Los Angeles-native hit her low at the Rio Olympics, losing in a shocking first-round upset with sister Venus in doubles, and bowing out in the third round of the singles.
Trouble began with her withdrawal from the Hopman Cup in January with an inflamed knee, while she retired from the Rogers Cup in July with shoulder inflammation. The same injury pulled her out of the Western & Southern Open in Cincinnati in August.
If anyone can rejuvenate Williams' career, it's the 46-year-old coach of Greek and French extraction. Nine of her 22 grand slam wins have been achieved since she began working with Mouratoglou -- the first instructor to take the reins from outside of her family.
At the time, Williams was coming off her most disappointing grand slam result since turning pro: A 2012 first-round French Open knockout at Roland Garros.
"I wasn't really thinking of having Patrick as my coach," Williams told CNN. "I had just had an early exit at a grand slam, and I didn't really want to go home. I just wanted to train and get better.
"I met Patrick ... and I liked what he said, and the kind of the things he did," she added. "And before I knew it, it was 'Well do you want to come with me to Wimbledon?' And 'Do you want to come with me to the Olympics?' It was really organic how it worked out.
"We had a long discussion about how he worked, and I had a discussion about how I worked, and we were able to meet in the middle."
With Mouratoglou's backing, Williams bounced back from her French Open flop in 2012 to win Wimbledon and an Olympic gold in successive months, and would go on to play the most dominant tennis of her career.
But their relationship wasn't smooth sailing from the get-go, and Williams took time to gel with her new coach.
"With me, there are rules to respect," he wrote. "One, when you arrive in the morning, you say hello. Two, when I speak to you, you look at me and you answer.
"It was a key moment because I established a relationship where I had authority and there was respect. I think that was indispensable."
They now have a calm working partnership, Mouratoglou says.
"I'm not a great fan of shouting," he told CNN. "Sometimes I've done that, but it's just for short-term results. We never get angry with each other. If we are, we can talk and sort it out."
Mouratoglou's philosophy with his most famous pupil also translates to his tennis academy, now located just outside of Nice on a sprawling campus that features 34 tennis courts.
To meet the needs of 150 youth members who live there full-time, the facility also boasts 85 bedrooms, 15 classrooms and a library.
Grades are taken seriously, and the academy -- previously based in Paris -- sends more than 60 players to US universities on scholarships every year.
All of that can make other coaches jealous, Mouratoglou admits.
"I'm working incredibly hard because I love it," he said. "My job is to work with kids, help them achieve their dreams, help them reach their full potential.
"I do the same with Serena. If you look at the Serena with 13 grand slams and the Serena with 22, she's a different person.
"She was a champion, (and now) she's a legend."