June 22 (Reuters) - Comcast Corp's CMCSA.O NBCUniversal and Alphabet Inc's GOOGL.O Google are leading the race for a tie-up with Netflix Inc NFLX.O to help it create an advertisement-supported subscription plan, the Wall Street Journal reported on Wednesday, citing sources. Google, which already has a relationship with Netflix as a provider of ad-buying tools, could pursue an exclusive deal with the company, the report said. Netflix said in April that inflation, the war in Ukraine and fierce competition had contributed to a loss of subscribers for the first time in more than a decade.