HBO has announced that it will briefly abandon its subscription model and allow viewers to watch the season 3 premiere of Lena Dunham’s Girls on YouTube just hours after its broadcast on cable in the US.

The move is an attempt to woo the show’s young and web savvy fanbase, which HBO clearly realises are more likely to turn to YouTube or illegal online streams if they miss an episode, rather than a subscription service like HBO GO.

“For us, this is an increasingly challenging demographic to reach with traditional means,” Sabrina Caluori, HBO's vice-president of social media and marketing, told Mashable.

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Girls made its TV return last night in the US, following the divisive "happy ending" of its second season that saw protagonist Hannah swept up in the arms of on-off boyfriend Adam.

HBO has maintained a "social first" approach to its promotion of the show, continuing to post all manner of Vines and GIFs through its social media accounts as teasers and even dabbling in transient messaging service Snapchat.

It has also re-launched its popular Tumblr account for the new series, fearing its previous 'What Should We Call Girls' incarnation was becoming tired and rechristening it 'Girls HBO'.

"The What Should We Call Girls version was successful at the time, but memes, by their nature, are fleeting," Caluori added. "The automatic fan behaviour was GIFs. By opening it up to the broader theme now, we can take it to the next level."

Another of HBO’s biggest draws, Game of Thrones, returned today with a trailer for its highly-anticipated fourth season that promises more struggles for power in the fictional world of Westeros.