As Gautam Adani Enters Mukesh Ambani Turf, Asia's Richest Prep For Battle

After peacefully expanding in their respective domains for over two decades, Asia's two richest men are increasingly treading the same ground.

In June, billionaire Mukesh Ambani and his aides ran into an unexpected dilemma when debating where to train the dealmaking lens of his empire next.

Ambani's Reliance Industries Ltd. was contemplating buying a foreign telecommunications giant, when word reached them that Gautam Adani -- who had overtaken Ambani as Asia's richest man a few months earlier -- was planning to bid in the first big sale of 5G airwaves in India, according to people familiar with the matter.

Ambani's Reliance Jio Infocomm Ltd. is the top player in India's mobile market, while the Adani Group doesn't even have a license to offer wireless telecommunications services. But the very idea that he might be circling ground so core to Ambani's ambitions put the tycoon's camp on high alert, according to the people, who asked not to be named discussing information that isn't public.

One set of aides advised Ambani to pursue the overseas target and diversify beyond the Indian market, while another counseled conserving funds to fend off any challenge on the home turf, according to people familiar with the discussions.