R&B star Usher [ tickets ] has pushed the beginning of his world tour to April after injuring his shoulder during rehearsals.

According to published reports, he dislocated his shoulder while practicing a back flip and required rotator cuff surgery at an undisclosed Los Angeles hospital on Monday (11/12).

The tour was slated to begin on Dec. 6 in Minneapolis. It is unclear if Ray J. (the brother of singer-actress Brandy) and Fabolous, originally scheduled to serve as the tour's opening acts, will support on the rescheduled dates. The new itinerary wasn't available at press time.

Usher's tour was planned in support of the platinum-selling "8701" (Arista), which currently sits at No. 12 on the Billboard 200 and No. 8 on the Top R&B Hip-Hop albums charts. The first single, "U Got It Bad," is at No. 1 for a second week on Billboard's R&B/hip-hop singles chart and at No. 16 on magazine Radio & Records' Urban and Urban AC chart.

On Nov. 30, Usher expands his acting resume with a starring role in "Texas Rangers," an oft-delayed western featuring Dylan McDermott ("The Practice") and James Van Der Beek ("Dawson's Creek").

Usher was one of the many artists who paid tribute to Michael Jackson during his "30th Anniversary Special," which aired on Monday.