In the fight between Tencent and Alibaba for China's emerging mobile payment market, cab-calling services have become the surprise battlefield.

Smartphone apps Didi (Tencent) and KuaiDi (Alibaba) are competing for the business of the taxi-riding public.

Didi said last Tuesday that if passengers pay cabdrivers via WeChat (Tencent), they will get a subsidized 12 yuan ($1.90) discount.

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Hours later, rival KuaiDi made a similar promise to cut "always 1 yuan more than our competitor" off the price, if the payment goes through Alipay.

Alipay currently leads mobile payments with nearly 300 million registered users, 100 million of whom use mobile phones.

Outright war in the fight for mobile Internet market share does not seem avoidable because people want to be connected all the time.

Alipay wins users mainly through money transfers and credit-card payments, while Tencent attracts mobile payment service users through its mobile social-networking and game apps.

In the personal finance arena, Yu'E Bao, an online product launched by Alipay and Tian Hong Asset Management Co Ltd, has attracted 49 million users, who deposited more than 400 million yuan in less than a year.

Tencent and China Asset Management launched online asset management services in January. Users can deposit money and receive up to 7 percent of the annualized seven-day interest.

"The adoption of mobile payment is slow, and application scenarios are limited. The players are very active in various fields of competition, but the majority of mobile payment services and products are still in the pre-commercial phase," according to a Trends and Prospects of Mobile Payment Industry in China 2012-2015 Report released by Deloitte.

Hu Yanping said the acquisitions by Tencent and Alibaba are "only the first step".

"Companies will seek ways to integrate all mobile services to make a profit and even change people's lifestyles," he said.

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Videographic: the battle of the taxi apps