You might not have had Justin Bieber down as the competitive type, yet the pop idol has decided to out-do the other celebs taking on the ice-bucket challenge.

Not content in getting soaked in cold water for a good cause once, the 20-year-old took his top off and did it again shirtless for the benefit of his fans yesterday.

Biebs had been nominated for the challenge by his manager Scooter Braun, who had previously done it himself.

The star posted two clips of himself doing it on his Instagram page - and then aimed high with his own nominations.

On the first vid he wrote: "I accept, now I nominate @Theellenshow my main man President Barack Obama and @chrisdelia #alsicebucketchallenge"

And on the second one, instead of nominating his showbiz pals he risked alienating his entire fanbase instead.

He wrote: "I Nominate all the #BELIEBERS for the #alsicebucketchallenge."

We showed you a video of Taylor Swift doing the challenge yesterday.

The viral stunt is in aid of the American ALS Association - which supports research into and helps people suffering from amyotrophic lateral sclerosis.