Superstar singer Beyonce has said she lip-synced the national anthem at President Barack Obama's inauguration because she wanted her performance to be flawless.
After opening a news conference on Thursday by belting out The Star-Spangled Banner - as if to leave no doubt of her capabilities - Beyonce answered questions from reporters about the inauguration show and her upcoming Super Bowl appearance.
She is scheduled to perform during the Sunday championship football game's half-time show.
The singer called herself a "perfectionist" and said various conditions - including cold weather and lack of time to practise - led to her decision to use a pre-recorded track at Mr Obama's ceremony.
She said: "I practise until my feet bleed and I did not have time to rehearse with the orchestra.
"Due to no proper sound check, I did not feel comfortable taking a risk.
"It was about the president and the inauguration, and I wanted to make him and my country proud, so I decided to sing along with my pre-recorded track, which is very common in the music industry.
"I'm very proud of my performance."
All inaugural performances are pre-recorded ahead of time as a fallback.
Beyonce has trailed photos and video of herself preparing for the Super Bowl show, which is expected to be the biggest audience of her career.
Last year's half-time performance by Madonna was the most-watched Super Bowl show ever, with roughly 114 million viewers - more than watched the football game itself.