Asked if her latest comeback represented the biggest test of her career, Mouratoglou said: "It probably is... now she is 36, just had a child, a second blood clot, has gone more than a year without any competition".
Navratilova, who has 18 grand slam singles titles of her own, says it is not impossible that Williams can win and, even if she fails to do so, makes her favourite to triumph at the Miami Open later this month.
Williams conceded she's sometimes surprised by how well she's playing when the new mother reminds herself she thought she "would have retired six years ago".
The 90th annual Academy Awards took place on Sunday night in Los Angeles, with many of Hollywood's heavy hitters congregating to honor some of the best works of film over the past year.
"It was good", she said of the experience.
Samsung Galaxy S9 Plus Camera Now DXOMark's Best-Rated Camera, Scores 99
How great are Samsung Galaxy smartphones at taking photos and video? "The S9 is designed specifically to take advantage of that". In addition to producing the screens in the Galaxy S9 , Samsung is a screen vendor for Apple's iPhone X .
"I think everyone should have high expectations", said Williams, who will be unseeded at Indian Wells and open her campaign against 53rd-ranked Zarina Diyas of Kazakhstan. She doesn't just want to show up and give somebody a leg up so they can say "oh I beat Serena". No matter what shape you think Serena is in, Diyas cannot play at that level if she expects to get the victory here and advance in this big tournament. I can't go and say, "I expect to lose", because that's just something I'll never say.
Williams, a victor of 23 Grand Slam titles, is in the same quarter of the draw as older sister Venus. It's just a little different, I'm just expecting to see where I am more than anything.
'In two months I'll be way better but you have to start somewhere.
Talking about competing in the upcoming Grand Slams tournament, Serena was quoted as saying, "If I want to play in those grand slams and play well then now is the ideal time to start". "She's going to bring that instinct on the court with her, so I don't think she's too anxious about that".
Another motivating factor, should Williams ever need one.
Navratilova added that Williams' style of play means she will soon be competing at her best level.