Dan Gilbert and Warren Buffett are more than friends.

The billionaires' mutual admiration could turn into a deal worth billions of dollars, as Gilbert, chairman of Detroit-based Quicken Loans Inc., is seeking to acquire Internet pioneer Yahoo Inc. with the backing of Buffett's Berkshire Hathaway Inc., according to Reuters.

Both groups have been hush about the bid, but Buffett did clarify his involvement in an interview with CNBC on Monday.

"I'm an enormous admirer of Dan and what he has accomplished in Quicken Loans," Buffett told CNBC. "Yahoo is not the type of thing I'd ever be an equity partner in. I don't know the business and wouldn't know how to evaluate it, but if Dan needed financing, with proper terms and protections, we would be a possible financing help."

Such an investment, if it happens, would be a new direction for Gilbert, who has expanded Quicken Loans into the country's third-largest mortgage originator, become downtown Detroit's dominant real estate investor and bought the National Basketball Association's Cleveland Cavaliers — who will play the Toronto Raptors in the Eastern Conference Finals starting this week. He has not previously publicized investments in major publicly traded companies.

Basketball played a role in Gilbert's relationship with Buffett.

Buffett came to Detroit in November 2013 to kick off the Goldman Sachs 10,000 Small Businesses program, which Buffett co-chaired. The $20 million program trained entrepreneurs in major U.S. cities as a way to create economic growth.

Gilbert became Buffett's tour guide to Detroit. Shortly thereafter, they made a business deal. Together, they launched a $1 billion bracket challenge for anyone who could pick the winner of every NCAA March Madness tournament game correctly.

Gilbert's Quicken Loans offered the money, and Buffett's Berkshire Hathaway insured the prize. Quicken paid an estimated $10 million for the Berkshire insurance. Quicken, in turn, collected thousands of sales leads from participants for its mortgage originating business. And nobody won, against astronomical odds.

Gilbert later interviewed Buffett at the inaugural Detroit Homecoming event in 2014, which Crain's convened.

"I go along with whatever he (Gilbert) comes up with, and so far I haven't gone to jail," Buffett said at the time.