So yesterday I gave Beyonce props for her singing of the National Anthem at yesterday's Presidential Inauguration ... But it turns out I should have been giving the REAL props to Kelly Clarkson. 

Why?

A spokesperson for the U.S. Marine Corp Band -- which provides the music for the Inauguration -- tells TMZ, Beyonce mouthed the words to a pre-recorded studio version of "The Star-Spangled Banner."

But the rep added, Kelly sang "My Country 'Tis of Thee" WITHOUT the help of a backing track.

YOU GO KELLY!!!