(CNN) -- Yes, Beyoncé can sing -- all by herself, thank you very much. That much she showed Thursday, when she opened her appearance before reporters in New Orleans -- where she's set to headline the Super Bowl XLVII halftime performance Sunday -- with a stirring, a cappella rendition of the national anthem. It was the same tune she sang just over a week ago at the inauguration of President Barack Obama But on that momentous occasion, Beyoncé admitted on Thursday, she had some help. The world-renowned pop singer told reporters that "she decided to sing along with my prerecorded track," a decision she made in part because she didn't have time to rehearse with the U.S. Marine Band and had had "no proper sound check." "I did not feel comfortable taking a risk," Beyoncé said of what she called "a very, very important, emotional show for me." "I wanted to make (Obama) and the country proud." The admission about the January 21 performance wasn't a complete shock. A spokeswoman for the Marine Band initially said Beyoncé "was not actually singing" the national anthem. Hours later, the band backed away from the spokeswoman's remarks, releasing a statement that said the group was not in a position to know for sure. But that hardly stopped the speculation that one of America's most famous contemporary singers had lip synced at one of the nation's most important moments. Two days after the inauguration, an inaugural official who asked not to be identified said Beyoncé "did not sing live," even though "she was spot on" in her prerecording, which was taped separately from the band and then married together. The Houston native had been mum on the topic until she discussed the matter Thursday. Calling herself a perfectionist who will typically "practice until my feet bleed," she conceded worrying about potential problems during "a live television show" taking place outside on a chilly Washington day. Even with all the hubbub -- and her insistence that "I always sing live," with that exception -- Beyoncé expressed no regrets about her rendition of "The Star-Spangled Banner" in front of the Capitol. "I'm very proud of my performance," she said. The 31-year-old said the practice of performers singing along with prerecorded tracks is common in her industry. Still, she promised she won't be doing it Sunday during the Super Bowl halftime show. "I will absolutely be singing live," Beyoncé said. "This is what I was born to do." As to exactly what she'll do, and with whom, she didn't say much Thursday, dodging a question about whether she will be joined by her Destiny's Child bandmates or her husband, critically acclaimed rapper Jay-Z. While Alicia Keys and Jennifer Hudson (the latter singing with the choir from Sandy Hook Elementary, the Connecticut school where 20 children were killed in December) also will perform, Knowles will command the stage once the San Francisco 49ers and Baltimore Ravens break for halftime. "I'm trying to learn to live every moment, because these moments are not promised to us," she said of her excitement, recalling how she took off her shoes and ran the first time she set foot on the Superdome field. "This is such a huge opportunity." It's also a huge challenge, including working on a stage that needs to be put together in just more than seven minutes, condensing her career into one 12-minute set, then performing in what is often any given year's most watched program on television. Beyoncé admitted being nervous, but also said that after more than four months of preparation, she's prepared. "I've had a 16-year career, and all of the things that I've done have prepared me for this," she said. "I'm ready."