As Visa, Mastercard and American Express prepare to enter China for the first time, one of their biggest competitive threats will come from a company that doesn’t issue credit cards.

Jack Ma’s Ant Financial, already the biggest player in China’s $27 trillion payments market, is leveraging its ubiquitous Alipay mobile app to mount a rapid expansion into consumer lending.

Instead of issuing cards, Ant allows customers to borrow with a few taps on their smartphones. The loans are wildly popular among China’s army of mobile-savvy shoppers, who often lack formal credit histories but generate enough financial data via Alipay for Ant to make informed decisions on whether they will default. The company’s outstanding consumer loans may swell to nearly 2 trillion yuan ($290 billion) by 2021, according to Goldman Sachs Group analysts, more than triple the level two years ago.

“The consumer loans business has been growing at breakneck speed, but there are so many untapped users,” Huang Hao, president of Ant’s digital finance operations, said in a phone interview outlining the company’s strategy.

Ant’s push into China’s 10 trillion yuan market for short-term consumer loans will make it an even more formidable challenger to U.S. card companies, which are counting on the world’s second-largest economy as a source of long-term growth.

Many Chinese consumers and businesses are ditching credit cards as Ant and its main competitor Tencent Holdings make app-based spending, borrowing and investing increasingly user-friendly. In a Nielsen survey of more than 3,000 Chinese people born after 1990, nearly 61% said they use online consumer credit while only 45.5% had a credit card.

“For credit card companies coming to China, the biggest challenge is how to attract people,” said Zennon Kapron, managing director of Singapore-based consulting firm Kapronasia. “A lot of Chinese millennials are digital first, used to using Alipay as their first platform for payments, loans and wealth management.”

The card giants are moving forward in China anyway.