With his little brother launching his biggest film to date, Chris Hemsworth made sure he was on hand to offer support.
The Thor star looked proud of Liam as the handsome pair walked the red carpet in London, much to the delight of the ladies in the crowd.
Miley Cyrus's boyfriend, 22, has been thrust into the spotlight as one of the main characters of The Hunger Games, the big screen version of Suzanne Collins' adventure novel.
In it he plays Gale Hawthorne, childhood friend and love interest of Jennifer Lawrence's character Katniss Everdeen.
The pair are separated when she must take part in The Hunger Games, an annual event where selected children of the 12 districts of the post apocalyptic world of Panem must fight to the death.
Chris started out on Aussie soap Home & Away but is probably best known for playing Marvel comics hero Thor.
Liam, meanwhile, cut his teeth in Neighbours before breaking into films.
He auditioned for Thor but his big brother beat him to the role, then landed the part that would net him a pop star girlfriend, playing Miley's love interest in The Last Song.
The siblings aren't the only actors in the family. Their older brother Luke is a small screen star, and the 30-year-old regularly appears on Aussie TV.
The three brothers were raised for some time in the Outback, and 28-year-old Chris in particular has childhood memories of "crocodiles and buffalo".
Also supporting the Australian actor was his sister-in-law Elsa Pataky, who is eight months pregnant.
Conscious of not upstaging her brother-in-law, the Spanish actress wore a simple black dress which was largely covered up by a long red coat.
Others attending the film's European unveiling included Liam's co-stars Jennifer – who stepped out in a golded gown, as she did at the LA premiere – and Elizabeth Banks.