Angelique Kerber may be Australian Open defending champion but Serena Williams' coach does not believe the world number one is the American's main threat in Melbourne.
Kerber has battled her way into the third round of the first grand slam of 2017 with three-set victories over Lesia Tsurenko and Carina Witthoeft.
The German has been in fine for the past 12 months to claim her first two grand slam titles - she also won the US Open - while also finishing runner-up at Wimbledon and WTA Finals.
She usurped Williams as the best player in the world during 2016 and remains at the summit.
However, Mouratoglou believes the German's scratchy start to the new year reduces her threat to Williams as the American looks to win a record-breaking 23rd grand slam.
"To be honest she [Williams] doesn't look at it as people who can beat her, and I like that, she always thinks it's up to her," he told the Tennis Podcast.
"When Serena's at her best I don't think anyone can beat her, but she has to be at her best.
"The ones who we expect to be the most dangerous are Kerber, [Garbine] Muguruza all those players, but I don't think they are playing their best tennis at the moment.
"I think [Karolina] Pliskova is playing really well from what I've seen in the last matches, and [Johanna] Konta, she was very impressive in Sydney.
"I think those two are in great shape and might be the most dangerous ones in the tournament."
Williams moved level with Steffi Graf on 22 grand slam titles with her Wimbledon success in 2016 - where she beat Kerber - but going past the German legend proved a big burden at Flushing Meadows.
Mouratoglou says reaching the magical 23 is not something Williams should focus on.
"Pressure is something that everyone talks about but nobody knows what it is, because unless you have experienced that you have no idea.
"For Serena the pressure is another level.
"She doesn't think about 23 every day, of course not, but she feels that pressure. I think she is great to deal with pressure, she has showed it all her career, it's at a different level at the moment but she will find a way, as she always has done."