The 29-year-old has more followers on Instagram than Virgil van Dijk, Tottenham or Pele - her 6.3 million followers roughly the same as the number signed up to the Royal Family's official account.

Morgan is in the spotlight more than usual this month as she leads the USA's defence of their Women's World Cup title, but who is the woman behind the superstar billing? And how influential can she be on the continued growth of her sport?

"She's the face of the team and of the sport in the United States," Caitlin Murray, journalist and author of a book about the US women's national team, tells BBC Sport.

"She is the rare example of a soccer player who has transcended her own sport to hold a place in mainstream culture.

"Women's soccer fans are an especially passionate group and Alex Morgan is easily the most beloved player of all. When she walks by fans, the shrieking you hear is at a volume several decibels higher than for anyone else."

Author, graduate, goalscorer and 'kind, caring person'

California-born Morgan, who helped the USA win Olympic gold in 2012, rose to prominence at the 2011 World Cup - where she scored in their narrow defeat against Japan in the final, before helping them gain revenge in Canada in 2015.

Since then she has won a treble of trophies during a loan spell with Lyon, having previously lifted the 2013 title in the US with Portland Thorns.

Yet, it's not just on the field that the Orlando Pride striker has achieved success and notoriety. She has a degree from Berkeley, in political economy, having also authored a line of children's books.

Her series, called 'The Kicks', is all about teamwork, friendship and responsibility. So are those values representative of the player in private and on the training ground?

Marc Skinner, Morgan's head coach at club side Orlando Pride, said: "You can tell why she's the best in the world at what she does. She loves detail.

"In training, she is always asking questions, wanting to know how she can help her team and make herself better. I've found her to be genuinely really refreshing.

"She wants to be challenged. She wants to get better every day, and those are genuine words, from my experience. She expects high standards, high quality and she brings it so she should expect it.

"She's a tremendous person as well. Off the field, she's caring, she's kind."

'She has grabbed the torch for this team'

Jeff Kassouf, co-author of 'The Making of the Women's World Cup', has covered Morgan's career for a decade and has witnessed her ascent towards becoming "arguably the most recognisably woman who plays a team sport" in the world.

"The thing to know about Morgan's personality is that she actually prefers to be quite private," Kassouf says. "I'm sure that seems ironic, since she is just about everywhere on TV screens and magazine covers, but she speaks frequently of wanting to be able to go to dinner with her husband and not be bothered for photos.

"What has changed about her since she burst onto the scene nearly 10 years ago is that she is far more comfortable in that spotlight now. Through the years she has grabbed the torch as one of the voices of the team.

"She is one of the faces and leaders of the team's fight for equality, so she is truly much bigger than just the soccer world."

Former Birmingham City Women boss Skinner adds: "All of our girls look up to Alex, as a role model and that person you aspire to be like.

"If you aspired to be like her, you wouldn't go far wrong in the game."

A brand portfolio to match Ronaldo and Messi?

On the off-field efforts of Morgan, who is the youngest of three sisters, US writer Murray adds: "She takes being a role model seriously. Over the years, she's become more outspoken about women's issues and fighting against sexism.

"She also has a movie and a streaming series all aimed at young girls, and she says it's because girls need role models who allow them to feel more confident."

With those traits as a role model adding to Morgan's skill on the ball - which were highlighted to the world again by her five goals and three assists against Thailand - Morgan is a in high demand from sponsors, so what impact is she having on the game's commercial growth?

"This is a person who is the emblem of what women's football could potentially become," says Simon Chadwick, professor of sports enterprise at the University of Salford.

"If you look at her portfolio of partners, including Nike, McDonald's and Coca-Cola, the people with whom she's comparable in male sport are people like Ronaldo and Messi.

"Obviously compared to Ronaldo and Mess, her deals aren't as large or financially lucrative, but it's almost as though she is ahead of her time. Commercially she's really important to the women's game."

Could Morgan be a million-pound player?

Until recent years, the vast majority of transfers between clubs in the women's game have come at the end of a player's contract, with little or no cash exchanged, but with Morgan's wider appeal, ambassadorial awareness and social profile, could she buck that trend?

"For one of those top European clubs, looking at what she could bring them both in playing and commercial terms, why couldn't she be a million-pound player?" Chadwick continues.

"She's not just a great player but she's American. We know that, in terms of rights values in sport, the American market still is really important, accounting for about 40% of the global sport industry's size.

"Given her profile and success, a club could generate further revenues in the US market with her. That's linked to her playing performance, her record and her commercial performance too."

The USA meet Sweden in Le Havre later on Thursday (20:00 BST) for the chance to top Group F, with the match live on BBC Four for UK viewers.