CEO Tim Cook cheered on gamers at an event during a surprise visit to China, underscoring the market’s importance to the iPhone giant at a time when it faces mounting challenges.

Gamers gathered at an Apple store in Chengdu in southwestern China to play “Honor of Kings,” a game developed by TiMi Studio, which is owned by Chinese tech giant Tencent.

“The action-packed Honor of Kings started here in Chengdu and is now a global phenomenon on the App Store,” Cook said in a post on Chinese social media service Weibo.

The Apple CEO, also posted a video of himself cheering on gamers at the tournament. Honor of Kings is one of the biggest mobile games in China and a substantial revenue driver for Apple’s App Store in the country.

The Apple CEO’s visit to the company’s third-largest market comes just under a month after the iPhone 15, the company’s flagship smartphone, went on sale to a seemingly lukewarm reception, and as a beaten down Huawei attempts to make a comeback in the mobile market.

Counterpoint Research said in a note on Tuesday that iPhone 15 series unit sales for the first 17 days of sales in China is down 4.5% compared with the iPhone 14.

That comes after Chinese tech giant Huawei last month reportedly launched a smartphone containing a high-end semiconductor and 5G connectivity, despite U.S. sanctions that have sought to stop that from happening.

Huawei was once the biggest smartphone maker in China, and Apple’s biggest challenger, before U.S. sanctions cut it off from key technology it needed to compete, causing it to fall to the No. 6 spot.

But as recently as Monday, Jefferies analysts published a report that said Huawei has become the No. 1 smartphone maker in China, overtaking Apple.