Among the four projects in the running for the much-coveted prize is Will Alsop's 'bag' scheme, which was drawn up in collaboration with Toronto-based architect Quadrangle.
The other finalists are Zaha Hadid, Canadian master Arthur Erickson with Nick Milkovich and Edmonton's Dub Architects, and Randall Stout from Los Angeles.
The winning scheme will create a 'gallery of the future that would be a place of experimentation, entertainment and education for the community, and not just a place to install art.'
The EAG brief asked entrants to devise a project to include the renovation of the original building and add an additional 2,800m 2.
A winner is expected to be announced by the gallery's Board of Governors on October 11.