Serena can complete 2014 Grand Slam, says coach
Serena Williams of the US celebrates after defeating Victoria Azarenka of Belarus in the women's final at the Brisbane International tennis tournament on January 4, 2014
Steffi Graf, in 1988, was the last woman to win the Australian Open, French Open, Wimbledon and US Open in the same year.
But Mouratoglou believes Williams is in prime position to repeat the German star's feat starting in Melbourne from Monday, where she has already been champion on five occasions.
"With Serena, everything is possible. Look at the level she plays at at the moment," Mouratoglou told the BBC.
"She's beaten all the top players many times, so you can aim that high.
"Of course it would be exceptional because it's crazy to do that. It's happened just a few times in the history of tennis -- but she can do it and the goal is to do the best possible in all four Grand Slams. So why not?"
The 32-year-old Williams completed a non-calendar Grand Slam in 2003 and last year won the French Open and the US Open to take her majors total to 17.
Former great Martina Navratilova has already said she expects the American to equal her total of 18 Grand Slam singles titles at the Australian Open and go on to better Graf's record of 22.
Only Navratilova and Chris Evert (both with 18) and Graf have won more majors than Williams in the Open era.