And she's scheduled for another one on Saturday, paving the way for Stevie Wonder's return to the festival after rain canceled his set last year.
Thomas is scheduled to appear on the festival's largest stage at 3:05 p.m.; Wonder takes the same stage at 4:50 p.m. to close out the day.
"I'm honored at my age, 76, to still be called upon to perform," Thomas told The Associated Press. "I do it with great joy."
Thomas said she enjoys the crowd so much because most are fans who have followed her career since she began singing in the 1950s.
"I'm not singing to total strangers. I used to teach them all the latest dances and a lot of those people are still fans today. Some have become friends, who've brainwashed their kids into listening to my music. It's become a generational thing. They're bringing their kids and their grandkids and their great-grandkids. It's a wonderful way of being accepted."
She said her performances rarely include a set song list.
"If they ask me to sing their favorite song and I wasn't planning to, I will sing it," Thomas said. "That's why people come to the festival. They want to hear the songs that makes them feel closest to that entertainer. That's the relationship I have with my audience and I don't want them to leave disappointed."
The Grammy-winning singer is known for such hits as "Time Is On My Side," ''Ruler of My Heart," and "It's Raining."
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