Over the weekend, the single Omicron case—found in a 26-year-old woman—prompted Beijing authorities to test tens of thousands of people, lock down an apartment complex and office building—sealing people inside until they tested negative—and require anyone entering the city to get tested upon arrival. So far, authorities have not found another Omicron case in Beijing, but they have also not been able to track down the source of the initial infection.

The untraceable case raises the possibility that Omicron may already be spreading in Beijing, an outcome authorities nationwide have tried desperately to avoid. The nearby city of Tianjin has been under various levels of lockdown for the past week while battling its own Omicron outbreak.

The single case in Beijing may not seem significant while the U.S. routinely reports over 1 million COVID-19 infections per day and Omicron surges globally. But Beijing’s COVID-zero policy means that a small outbreak could prompt Beijing city authorities to impose neighborhood or citywide lockdowns on the eve the Games, a spectacle that was supposed to double as China’s COVID victory lap.

China has recorded just over 100,000 COVID-19 cases and 4,600 deaths since the beginning of the pandemic, a fraction of the toll the virus has wrought in most other countries. Until recently, hosting the Games this year seemed to offer Beijing an opportunity to showcase its COVID-zero success and demonstrate that its citizens have lived COVID-free lives within China even as the country has imposed harsh international border restrictions.

“The world is turning its eyes to China, and China is ready,” Chinese President Xi Jinping said in an address on Dec. 31. “We will spare no effort to present a great Games to the world.”

To Beijing, a “great” Games is one that appears normal to outside observers, with fans in stadium seats and on the sidelines of ski slopes.

Beijing is planning to host athletes and other Olympics-related foreign staff, media, and diplomats in their own bubble—or a “closed loop management system,” as Beijing calls it—that is separate from China’s broader population. China has barred foreign fans, but until recently, officials from the International Olympics Committee (IOC) appeared set on allowing local spectators view the Games.

“We need and we want to have spectators [at the Games],” Juan Antonio Samaranch Jr., head of the IOC’s coordination commission, told media last July. The Beijing 2022 Games also said on its website until this week that it would sell tickets to domestic fans.

“Tickets will be sold exclusively to spectators residing in China’s mainland, who meet the requirements of the COVID-19 countermeasures,” the website said. In December, Chinese officials said spectators could attend the Games but would be asked to clap instead of chant while watching the contests.

But on Monday, the IOC announced that Beijing will not sell tickets to Chinese fans.

“Given the current situation of the COVID-19 pandemic, in order to ensure the safety of all participants and spectators, it has been decided that tickets should not be sold anymore but be part of an adapted program that will invite groups of spectators to be present on site during the Games,” the IOC said in a statement. It is unclear how many spectators will be selected to attend the events, but at this point it appears that the Games will go ahead largely without fans cheering on the athletes.

Weeks ago, the Beijing Olympics appeared to provide a perfect opportunity for China to display its success against COVID, hosting an international event with thousands of domestic fans that could attend without worry of getting infected. But the prospect of Omicron-fueled lockdowns in Beijing and an Olympics with no fans at all may push Beijing to reset its expectations.

This article has been updated to reflect the IOC’s announcement that Chinese fans will not be able to attend Olympic events.