BOSTON (CBS) – Red Sox slugger David Ortiz’s daughter Alex kicked off the Pan-Mass Challenge by singing the National Anthem in front of thousands of cyclists.

Alex Ortiz, who sang the National Anthem in April prior to her father’s final Fenway Park opener, kicked off Saturday’s ride at Babson College as 2,700 cyclists looked on.

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“It was an adrenaline rush,” Alex Ortiz told WBZ-TV’s Kathryn Hauser. “I was very nervous. I was shaking.”

The 15-year-old said she has been coming to the Pan-Mass Challenge for about 10 years, and her mother has ridden in it several times.

She said she was shocked to learn that the event raised $45 million last year alone, and $500 million since its inception.

“I was freaking out because that’s an insane accomplishment,” said Alex Ortiz. “And all for cancer research, something we fight for every day. I was just choked up. I couldn’t believe it.”

Alex said she has performed the National Anthem so many times that it is “almost muscle memory,” but she adds that she never sings it the same way twice.

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The Pan-Mass Challenge continues Saturday and Sunday as riders try to reach their fundraising goal of $46 million this year.