For most e-commerce players in China, this Sunday may probably be the very day they both love and worry about.

A large online shopping promotion, most likely the biggest ever, will come as an opportunity for many to cash in on — and prove a huge test too.

The promotion, initiated by e-commerce giant Alibaba Group Holding Ltd, includes more than 10,000 vendors on its that will offer half-price discounts on Sunday. Major e-commerce websites, including Jingdong Mall and Amazon China, will also hold promotions that day, making the shopping event even bigger.

In the office of Beijing Jiuxian E-Commerce Co Ltd, a Beijing-based spirits seller, there is not just a smell of spirits, but also one of “war”.

A digital clock at the office door counted down seconds for the upcoming promotion; a red banner hanging high on the wall to boost morale; and a “war map” including more than 100 work divisions occupied the most conspicuous place in the office.

“I am very excited and curious, but also wonder whether we can make it,” said company Chairman Hao Hongfeng, who talked in his office after days of hard work.

The company sold spirits worth 10 million yuan ($1.6 million) in the event last year. Hao aims to boost sales by 10 times that amount on Sunday, which, if successful, will be the equivalent of a month in sales during the off-season.