Doing real stuff sucks: Back to reality for Justin Bieber after spending the day flirting with Heidi Klum on Next Top ...

PUBLISHED: 14:10 EST, 8 June 2012 | UPDATED: 16:03 EST, 8 June 2012

He spent yesterday hanging out with supermodel Heidi Klum so its no wonder Justin Bieber thinks Doing Real Stuff Sucks.

The Boyfriend hitmaker was spotted leaving the Ritz Carlton Hotel on Potsdamer Platz square in Berlin today wearing an oversize sweater with the slogan in large letters and he can be forgiven for the sentiment.

Justin kept it casual in black jeans, trainers, sunglasses and a backpack as he strolled around the city with minders, to keep the ever present Beliebers at bay.

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Back to reality: After spending yesterday flirting with supermodel Heidi Klum, it was back to earth with a bang for Justin Bieber as he continued promoting his new album

At least some people are happy: Justin thrilled fans by stopping to sign autographs in Berlin today

However, he did st! op to si gn some autographs for his dedicated fans who were overcome by their proximity to their idol.

It was a very different day for the 18-year-old superstar, who spent yesterday filming an appearance on the finale of Germanys Next Top Model.

The cheeky singer made sure he got a hug from stunning Klum, despite the fact that at 39 she is over twice his age and he is loved up with teen star Selena Gomez.

That's more like it: Bieber was thrilled to get up close and personal with supermodel Heidi Klum when he performed on Germany's Next Top Model

However, Justin looked delighted as he got to grips with the model, who was clad in a slinky, backless silver gown.

He was also charmingly flirtatious as Klum interviewed him for the programme.

Justin put on an energetic show as he took to the stage with a group of backing dancers for a performance of Boyfriend.

Energetic performance: Justin and his dancers wowed the crowds with their performance on the reality TV show

Boyfriend! Justin performed his latest single on the season finale of the Germany's Next Top Model

Justin signs autographs while guarded by a security guard during the reality TV show

Starting at the base of the stage, the room erupted with cheers as he came down the stairs to get up close and personal with fans.

While he was at the show Justin tweeted Lots of beautiful ladies running around the hallways at Germany's Next Top Model. You're all winners in my eyes.

After the show he and Heidi sent each other cheeky messages on twitter with Heidi writing #Thank you @justinbieber for making us #BELIEVE in Germany!! You rock!

Flirty! Heidi and Justin exchanged flirty messages on twitter after the show

Don't be embarrassed @heidiklum - you make me nervous and sweaty too ;) was Justins flirty reply.Justin is currently on a tour across Europe to promote his upcoming third studio album Believe.

However, he will take a break from his promotional duties this weekend to perform at Wembley Stadium tomorrow for the Capital FM Summertime Ball 2012.