Usher was forced to postpone the Jan. 12 launch of his OMG tour in Europe this week, due to sudden illness. The R&B singer was diagnosed with a paranasal sinus infection, which prompted him to push his Berlin show to Thursday night (Jan 13.), but the rescheduled performance ended in boos when he walked off the stage early.

According to a concert attendee who wrote into, Usher was approximately 40 minutes late to his show at Berlin's 02 World Arena, and when he finally arrived, he was unable to perform his set. After taking several breaks, and botching a song or two, Usher reportedly left the stage, putting a sudden end to the show.

"There were five songs (sung only playback not live), interrupted by several 5-minute breaks during which Usher left the stage without further announcements and a DJ took over for a few minutes," the anonymous fan wrote. "Then the fiasco took its course: as Usher sang a song which he sang wrong and crooked, he interrupted the song and gave an excuse for the cancellation of the previous day. While trying to sing everybody booed at him. Usher's reaction: he sat down and put his head on the microphone. After he had sung for another 10 seconds, he went off the stage. The lights went on and the concert was over."

Usher has postponed his concert in The Netherlands this evening (Jan. 14) until March 1.

Watch Usher's Performance in Berlin