Samsung Pay launches in China. Its biggest challenge is Samsung’s irrelevance.

Five weeks after Apple Pay rolled out in China, Samsung is today launching its own mobile payments system in the country.

Samsung Pay allows owners of certain Samsung phones to pay for things in-store after tying a bank card to the app. Samsung’s system works at most stores and restaurants in the country due to the Korean firm tying up with China UnionPay, the nation’s main card network. Shoppers hold their phone near the UnionPay dongle that most cash registers in China have, and then authenticate the payment by scanning their fingerprint on the phone’s “home” button.

Samsung will be up against not just Apple Pay but also homegrown mobile payment services from WeChat, the nation’s top messaging app, and Alipay, the Alibaba-backed mobile wallet app.

Apple Pay and Alibaba’s Alipay among the payment options at a supermarket in China.

But the biggest challenge for Samsung Pay is Samsung’s growing irrelevance in the Chinese market. Samsung was China’s top smartphone maker in 2012 and 2013, but then Xiaomi took the throne in 2014 as well as last year.

In 2015, Samsung crashed out of the top five phone brands in China in terms of sales, according to data from IDC.

Apple Pay at a Costa Coffee in China.

Samsung’s shrinking customer base in China will limit the revenue it can get from Samsung Pay as well as its potential visibility in stores. And not all Samsung phones support cashless payments in China yet. Only the Samsung Galaxy S7, Galaxy S7 Edge, Galaxy S6 Edge+, and Galaxy Note 5 can use the system at the moment, Samsung said today. Support for more devices that already have NFC may be added later.

Today marks Samsung Pay’s official launch in China after a month of quiet testing.

Apple Pay also works in China via a partnership with China UnionPay.

See: Xiaomi needs to go upmarket