ONLY two companies remain in the battle to win Cathay Pacific Airways' $250 million a year worldwide advertising account. McCann Erickson and Ogilvy & Mather have been short-listed from seven companies invited to make presentations. The five firms which lost out in the initial review were Ball Partnership, Grey Hongkong, Bozell, J. Walter Thompson and Dentsu, Young & Rubicam. The two short-listed agencies have been asked to provide a more detailed pitch next month after being given an expanded brief to enable them to make more in-depth proposals. Cathay expects to be able to announce the winner in June. The hunt for an advertising agency came after Cathay and Leo Burnett decided to end their partnership after 10 years. It was Leo Burnett which coined the airline's ''Arrive in better shape'' catch-phrase. Their parting came as a shock in the industry. Observers had considered Leo Burnett's hold on Cathay's advertising account close to unbreakable. But Cathay decided that after a decade it was appropriate to ask other agencies for their respective visions for future corporate identity. Leo Burnett was invited to pitch again for the business, but declined. Mr Alistair Blount, Cathay marketing communications manager, said the airline's new corporate positioning and corporate identity might not come about until the end of next year or 1995. Cathay was not only looking for a new advertising agency, but a whole new livery, he said.