LONDON (Reuters) - British director Guy Ritchie says the biggest danger when making the sequel to his 2009 box office hit Sherlock Holmes was complacency. Madonnas former husband was on the red carpet in London late on Thursday for the European premiere of Sherlock Holmes: A Game of Shadows, in which he again teams up with Robert Downey Jr. as the fabled super sleuth. Ritchie cranked up the action in his interpretation of Arthur Conan Doyles most famous creation, and his first outing proved popular with movie-goers who spent $524 million at the global box office. That impressive tally virtually guaranteed Hollywood would be back for more, and the sequel from the Warner Bros. studio hits US and British theatres on December 16. I do prefer the second one, Ritchie told Reuters. I think we just knew what we were doing more when we came to this one, we worked harder. We didnt want to be lazy and we knew that laziness was our enemy. It is easy to be lazy, so we had to trump it and with that comes a certain amount of anxiety and pressure. In A Game of Shadows, Holmes comes up against his nemesis Professor James Moriarty, played by Richard Harris son Jared who also starred in the hit TV series Mad Men. Jude Law returns as Holmes somewhat reluctant sidekick Dr. Watson, whose honeymoon plans are thrown into disarray when he is called on to help avert catastrophe in 1890s Europe. For purists, of course, theres almost certainly too much gunplay and noise ... but this is a Holmes designed to appeal as much to the 'Transformers generation as those steeped in his literary or even past cinematic exploits, Hollywood trade publication Variety wrote in its review.