The Tesla Model 3 was the best-selling electric car in the world in 2018, according to data firm JATO Dynamics. JATO says the Silicon Valley automaker sold about 138,000 Model 3s, beating out contenders like the flagship EV of state-owned Chinese automaker BAIC (92,000) and the Nissan Leaf (85,000). In total, Tesla sold more EVs than any other automaker in 2018, JATO reports.

The news comes at the same time that Tesla is starting deliveries of the Model 3 in China, the largest market in the world for electric cars. Tesla also recently started delivering Model 3s in Europe for the first time ever. Adding those new markets for the Model 3 is supposed to help Tesla increase sales of the car by more than 100,000 in 2019, according to recent estimates from the company.

Tesla releases sales and production figures every quarter, and it has previously touted the Model 3’s popularity compared to other midsized premium sedans from automakers like BMW, Mercedes-Benz, and Audi. But as Bertel Schmitt at The Drive points out, JATO generates its figures using vehicle registrations, which gives the numbers a more solid baseline.

Tesla’s tapping new markets for the Model 3 in 2019, but there are questions about demand

While Tesla plans to nearly double Model 3 production in 2019, the path to the top sales spot could be more challenging this year than it was in 2018. (Which is saying something, considering 2018 was the year of “production hell” and “delivery logistics hell.”) New markets like China and Europe will provide a boost to sales. But some analysts are wary that demand for the Model 3 is drying up in the US, because Tesla’s cars are no longer eligible for the full $7,500 electric vehicle tax credit, and the company still hasn’t started production of the $35,000 “standard range” version.

Tesla is also grappling with quality issues and problems with service that appear to be directly tied to its massive ramp up in Model 3 production and sales.

Tesla will face more all-electric competition this year, too, though it might not come from the most familiar names. Audi has been dealing with a slow rollout of its E-Tron SUV, and Jaguar has experienced similar struggles with the I-Pace. Mercedes-Benz is reportedly delaying the first deliveries of its own electric SUV, the EQC, as well.

Instead, Tesla’s biggest threat to the EV throne will likely come from China, including some of the companies that are already nipping at its heels. China’s largest automakers, like BAIC, also make smaller electric cars that are far more affordable than anything Tesla sells, and they have their own production facilities in China. Tesla needs to get its Shanghai Gigafactory up and running in order to make and sell Model 3s that can avoid the country’s 25 percent import tax, and that won’t happen until the end of this year at the earliest.

Meanwhile, Chinese EV startup NIO sold 11,000 cars in its first few months of production last year. The company has set its sights on providing customers with a Tesla-style experience, from its technology-filled cars, to building sleek stores where they’re sold. NIO has big ambitions — it recently went public in the United States — and will announce production and sales goals for 2019 in two weeks.

Still, Tesla has more than the Model 3. The company’s Model S sedan came in fifth on JATO’s list with 48,000 sold last year. The company finished the year with about 230,000 total electric cars sold, far above BAIC’s second-place sales figures of 152,000. Warren Buffett-backed automaker BYD came in third with 95,000 EVs sold last year, just ahead of Nissan, which sold 92,000 total electric vehicles.

Tesla also plans to reveal the Model Y crossover SUV later this year (potentially in China), with full volume production scheduled for 2020. By that time though, Volkswagen, Porsche, and even Ford will have their first serious EVs in production as well.