WIMBLEDON, England -- Being a celebrity herself didn't keep Serena Williams from being star-struck each time she met Michael Jackson.
Williams and Roger Federer were among the millions of fans lamenting the pop star's death on Thursday.
"Words can't express my shock and horror," Williams said Friday. "He was just a complete icon."
Williams said she met Jackson a couple times and became as giddy as any other fan.
"I was honored to meet him," she said. "I think any celebrity who met Michael Jackson was completely awed. I know I was. I kept thinking, 'Oh my God, oh my God. It's him, it's him.' So for me he was the celebrity of all celebrities."
Federer recalled going to a stadium in Basel, Switzerland, as a kid in the late 1980s with his sister and just standing outside to hear Jackson playing inside.
"There was such excitement that he would come," Federer said. "Obviously I love his music. ... A very sad moment, I think, in the music world. He touched many people. Same for me. But I'll obviously still listen to his music for many more years to come."
Williams wasn't able to name her favorite Jackson song but lauded his innovation, calling him "the greatest entertainer for me of all-time."
"He did things that no one else did," she said. "Like 'Thriller' is the best video ever made still to this day. The videos that he did for his songs, no one had ever even went that far. And he started a whole new trend with that. Dances, singing, beats, you know, everything."
Williams said she is "always online" and followed the news of Jackson's death on her computer.
"I think Michael Jackson, everyone listens to his music," she said. "It's like you think of the Beatles, you think of Elvis Presley, you think of Michael Jackson. Those are just lifetime icons that I've never forgotten. The things that he did was beyond iconic."
Former world No. 1 Andy Roddick said on his Twitter feed: "Oh my lord ... Michael Jackson died ... RIP sad and surreal. Regardless of what you think of him he was completely revolutionary and will be missed."
Tracy Austin, once a teen tennis prodigy, said: "He was an incredible talent, an incredible singer and an incredible dancer. It's along the lines of when Elvis passed away and everybody will remember where they were when they heard the news."
Information from The Associated Press and Reuters was used in this report.