Speculation has grown that the Irish brewing giants are set to be unveiled as backers of the PRO12 on Thursday morning, when next season’s fixtures will also be announced.
They will replace online banking group RaboDirect, who have been sponsors for the past three years, having taken over from Magners.
RaboDirect confirmed last year they would not be renewing their sponsorship of the league at the end of the 2013-14 season.
It’s understood the domain name www.guinnessPro12.com has now been registered out of Celtic League headquarters in Dublin.