Hollywood heartthrob Zac Efron says it was luck that propelled him to super-stardom, not his acting ability.

Speaking at the European premiere of his new romantic drama "The Lucky One," the 24-year-old actor said that he's had an easy ride so far, but it's now time to prove he's a legitimate thespian.

"I got into this in a very lucky way, but it wasn't the actor way, you know what I mean?" he said. "I would call what I had very much a lucky break.

"So, my goal over the past few years has been to take a step back, really learn about my craft, and prove to myself that it wasn't just a fluke, that I am here for a reason."

Efron shot to fame at the age of 18 starring in the 2006 smash hit "High School Musical." He went on to star in two more movies in that franchise.

After years of playing school boys, he's hoping his role in "The Lucky One" is a step toward shedding his teen idol image.

The movie is based on the best-selling novel by Nicholas Sparks and sees Efron star as a U.S. Marine sergeant who tracks down a beautiful woman (Taylor Schilling) whose photograph he believes saved his life in Iraq.

"I was proud to have taken this role — it was a scary choice," he said. "I didn't know if I could play a Marine. Everyone you talk to would say I am wrong for this part, but you know, at the end of the day it was a challenge, and I am proud. I think I pulled it off."

According to the film's director Scott Hicks, Efron is certainly a fully fledged, grown-up actor.

"He's a hard-working, committed actor, very committed to his craft and I just thoroughly enjoyed working with him," he said.

Also at the premiere was Efron's co-star Schilling. She also had nothing but praise for the actor, whom she called a "goofball."

"It was a blast," she said. "We never took ourselves too seriously. The work, yes, but we were fooling around the whole time."

"The Lucky One" hits U.K. theaters on Wednesday, May 2. It was released in the U.S. on April 20.