Chinese coffee startup Luckin Coffee extended double-digit gains on Tuesday noon, after the company posted its latest quarterly earnings characterized by explosive sales growth and store expansion.

Shares of Luckin Coffee soared over 12.9 percent around midday to trade at over 21.4 U.S. dollars apiece. As of midday, the company has been valued around 5 billion dollars in market capitalization.

During the third quarter (Q3), the coffee seller's total net revenues from products skyrocketed to 208.9 million dollars, up 557.6 percent year over year (yoy) and beating Wall Street estimates.

The eye-catching performance was primarily boosted by marked sales of its freshly brewed drinks, which reaped 160.2 million dollars, taking up 74.3 percent of total net revenues.

"Sales from freshly-brewed coffee drinks continued to maintain very strong growth, and we believe we will reach our goal to become the largest coffee player in China by the end of this year," Qian Zhiya, Luckin's CEO, said in the statement on Wednesday.

The coffee chain brand, often seen as a major rival of Starbucks in China, continued to scramble for a larger market share by rapidly expanding its sales landscape. Total number of stores by the end of Q3 registered 3,680, an upswing of 209.5 percent yoy.

As of Q3, cumulative number of transacting customers also shot up to 30.7 million, rising 413.4 percent yoy.

Yet its net loss in Q3 widened to 74.4 million dollars from around 69 million dollars in the same quarter last year, accounting for over 35.6 percent of the total net revenues.

As Luckin Coffee exceeded the high-end of its guidance range in Q3, the company raised the revenue guidance for the fourth quarter to a range of approximately 300 million-310 million dollars.

"China's coffee market remains highly underpenetrated, so we are very excited about the growth potential ahead of us," said Qian.