Josh Groban's "Full-Circle Moment"

Singer-songwriter Josh Groban's powerful baritone voice has captured audiences around the world -- and catapulted him to superstardom.

Groban was the best-selling artist of 2007, and his two albums, "Closer" and "Awake" have sold millions of copies.

He'll be performing the song "The Prayer" both on the Grammys show on CBS Sunday night with Andrea Bocelli, and with Celine Dion on her CBS special on Feb. 15.

"The Prayer," which won a Golden Globe Award in 1999 and a Grammy nomination, was done as a duet by Bocelli and Dion, and was used on albums put out by both.

It was penned by producer/composer David Foster and Carole Bayer Sager.

Foster, who's credited with discovering Groban, persuaded the young talent to do "The Prayer" for a Grammys rehearsal in 1999, and it wound up being Groban's first big break.

And doing it with Bocelli Sunday will be "such a full-circle moment for me," Groban observed to Early Show co-anchor Maggie Rodriguez Friday. "I'm so excited to not only be singing on the Grammys for the first time, but to be doing this song with Andrea is just huge for me, because I was a 17-year-old kid (when) I got called in (to the 1999 Grammys rehearsal) because he (Bocelli) was -- I guess his flight was late, or he was not feeling well. He wasn't able to make it to the rehearsal, and I came in and stood in for him."

He sang "The Prayer" at that rehearsal -- with Dion -- and many music luminaries who were there took note, sparking Groban's path to huge success.

Now, Groban gets to do "The Prayer' with Bocelli at the Grammys, which he calls "a huge thrill," and with Dion on her special.

You might say he's got all bases covered!