Rhys Ifans will join the cast of Elementary, alongside Jonny Lee Miller and Lucy Lui. The Welsh actor will play Mycroft Holmes, Sherlock's older brother. He is a definite feature in the season's premiere, airing in September but any possibility of further appearances has not been mentioned.

CBS' Elementary sets the traditional story of the famous detective in New York. Jonny Lee Miller and Lucy Liu starring as Sherlock Holmes and Dr Watson will, according to reports encounter Ifans in London. The season premiere will be set in the British capital as the deducing duo are forced to  deal with one of Sherlock's former cases. Ifans as Mycroft allows them to stay with him at Baker Street. Apparently a reasonable amount of sibling rivalry and tension will ensue. 

Rhys Ifans
Rhys Ifans, pictured at the 2012 Place for Peace dinner in London, is to join the cast of Elementary as Mycroft Holmes.

The producer and creator of Elementary, Robert Doherty, said in a statement to The Hollywood Reporter said "I've always been a tremendous fan [of Ifans] and feel very honoured to have him in the fold. Equally excited are Jonny and Lucy, both of whom have worked with Rhys in feature films".

Arthur Conan Doyle's famous detective stories have been adapted many times into a variety of films and TV series which have featured such actors as Basil Rathbone, Jeremy Brett, Robert Downey Jr and Benedict Cumberbatch. 

Benedict Cumberbatch and Martin Freeman
Benedict Cumberbatch and Martin Freeman as Holmes and Watson filming Sherlock in London.

The most recent UK adaptation of Conan Doyle's books sets Sherlock's adventures in London in a BBC series of the same name. It was announced in March 2013 that Benedict Cumberbatch and Martin Freeman would return as Sherlock and Watson in the third series due to be aired later this year. 

Elementary will air on 26th September on CBS.

Lucy Liu and Jonny Lee Miller
Lucy Lui and Jonny Lee Miller on a CBS 2012 summer publicity tour for Elementary in L.A.