``Nervous`` Bieber gets a boost on tour from Usher

London: A visibly nervous Justin Bieber was relieved when his mentor Usher stepped on stage to thrill the audiences and boost his performance for his first tour.

The 16-year-old revealed that he was "extremely nervous" ahead of his first My World concert in Hartford, Connecticut, telling followers on Twitter.com about his apprehension, reports The Daily Star. In successive posts on twitter, he wrote, "First tour ever. Little nervous. Don`t want to let u (sic) guys down... (Support act) Sean Kingston is on stage now!! Hartford is crazy... it`s almost that time. Wow." However, the Canadian sensation managed to calm down when R&B superstar Usher came on the stage while he was singing his hit ``Baby.`` After the show, Bieber tweeted, "2nite (sic) was just... well... I was scared. Didn`t want to let anyone down but the energy and the fans were incredible. Can`t wait to do this again! "My big brother Usher came to support me and even ran out on stage and surprised me during BABY," he wrote. "(Now) on the bus heading to Trenton to the next show... just trying to take it all in from 2nite (sic). Just one of the greatest nights of my life," he added. ANI