Illness has forced vocalist Josh Groban [ tickets ] to postpone this week's appearances in San Diego and Phoenix, according to a statement issued by his manager.

"Josh has been diagnosed with an upper respiratory and sinus infection and his doctor has put him on 'bed rest' and 'complete vocal rest' for the next several days," manager Brian Avnet said. "The shows originally scheduled at Copley Symphony Hall in San Diego (2/2) and Dodge Theatre (2/3) in Phoenix are definitely going to be rescheduled and the tour is going to resume in Salt Lake City at the Delta Center on Feb. 5."

Groban, 22, performed his song "You Raise Me Up" during the Super Bowl pre-game show in Houston on Sunday (2/1), and last week he sang during Oprah Winfrey's birthday show, which airs on Friday (2/6).

"Closer," Groban's sophomore album, has been in The Billboard 200 album chart's Top 10 since its release on Nov. 11. He launched his tour in Boise, ID, on Jan. 22, and will be on the road through April.

Groban made a splash in the music scene with his self-titled 2001 debut, which--on the strength of the single "To Where You Are"--has sold more than 5 million copies to date, according to Reprise Records.

His career got a huge push internationally when he performed at the closing ceremonies of the Salt Lake City Winter Olympics, a show seen by more than a billion television viewers around the world, according to Reprise.