Gwyneth Coached by Robert Downey Jr. for 'Country Strong'

Actress Gwyneth Paltrow gained 20 pounds and practiced guitar until her fingertips bled to prepare for her role in "Country Strong," but it was good friend Robert Downey Jr. who guided her.

Portraying an alcoholic country star in the film, the Oscar-winning star turned to Downey, who has dealt with his share of addition problems in the past, to obtain insight into her character.

"There is a certain aspect of the addiction that went so far, I could only imagine it up to a certain point, but I couldn't imagine it as bad as she had it," Paltrow told "Extra." "He [Robert Downey] was amazing. He was very generous and kind of helped me understand addiction and how it works and from that point on I really felt like, okay I get it now."

Taping into her musical side for the role, Gwyneth also learned how to play guitar.

"It's much harder than it looks when you've never done it because first your fingertips, like mine, were bleeding and cracking," she said. "It was definitely a challenge, but it was great, 'cause now I can sing for my kids."

Gwyneth opens countrywide in "Country Strong" January 7.