Gwyneth Paltrow is worried she might get axed from Iron Man

Los Angeles - Gwyneth Paltrow worries about being replaced by a younger actress in the Iron Man franchise.

The 37-year-old beauty has portrayed Pepper Potts opposite Robert Downey Jr. as Tony Stark and his titular alter ego in three movies, plus ensemble film Marvel Avengers Assemble, and would love to return for another outing but isn't sure bosses would want her.

Asked if she will reprise the role again, she said: "I don't know. I'd like to do it. But they might swap me out for an 18-year-old Pepper Potts or something."

The Mortdecai star - who has children Apple, 10, and Moses, eight, with estranged husband Chris Martin - also admitted she "burned herself out" by throwing herself into work in her early 20s, and credits her career success partly down to "luck".

Speaking to the new issue of Harper's Bazaar magazine, she said: "It was a lot of good luck and a lot of hard work and a lot of being in the right place at the right time.

"But I burned myself out. I was doing three films a year, sometimes appearing in every single scene."

Despite her years of success, Gwyneth - whose parents are late actor Bruce Paltrow and actress Blythe Danner - insists she never set out to gain public recognition.

She said: "I just wanted to do what my mother did. I grew up watching her in rehearsals and struggling with lines and weeping with joy after a standing ovation. The camaraderie of the cast appealed to me so much - and it didn't have to be on an Oscar-winning movie."