You could force it to extract to the current directory (in spite of this being the default behaviour):
tar xvfz file.tar.gz -C ./
edit: I misread the requirements; this method won't extract the contents of a directory, only the directory itself, if that is what's been tarred. To extract the contents, so long as you know the structure of the archive, you can specify files to extract manually:
tar xvfz file.tar.gz directory/contents/you/want/to/extract/
This will extract the contents of directory/contents/you/want/to/extract/.