Tong also recruited actor Ai for his comedic skills, which he deployed to full effect in the 2017 hit Never Say Die, and actress Miya, a former yoga teacher whose physical talent and beautiful face reminded Tong of Michelle Yeoh and Maggie Q, two of the most influential action actresses of Chinese descent.

For the young performers, however, the film turned out to be a harsh challenge. They traveled to nine cities in five countries, filming many jaw-dropping action sequences ranging from "surviving" a furious lion on the African prairie to "escaping" the bombing of an aircraft carrier.

Yang, whose previous screen roles are mostly those of suave heartthrobs, sees it as a breakthrough to play a veteran-turned-security guard.

As preparation, Yang was coached in martial arts by Tong, who started his filmmaking career as a stuntman.

Admitting that Chan's classics such as Police Story and Who Am I? had etched themselves into his imagination since childhood, Yang says he was quite excited to have a chance to act alongside his idol.

"In all Chan's films, da ge ("big brother", the prevailing way of addressing Chan in Chinese cinema circles) always jumps from high buildings or other risky places without using stand-ins. Therefore, I think I should do as many of the stunts as possible myself. It will also become a valuable experience," says Yang, revealing he performed a nearly 20-meter-jump for a scene, his most nervous moment ever in his acting career so far.

Aside from stunt-training, Tong says the film used some expensive props, such as a golden sports car valued at around $120 million, and was shot at some global landmark attractions, including Burj Khalifa, the tallest building in the world.

Chan's character is called Tong Wun-ting, the same name as Stanley Tong's father.

Revealing it as a commemoration of his late father, the director says his father is the only person in his family who encouraged him to pursue his dream.

In his early years, when he was struggling to make his name in the Hong Kong film industry, Tong started as the stunt double for Maggie Cheung in The Seventh Curse and Chow Yun-fat's A Better Tomorrow.

He shot to fame after directing Chan's 1992 hit Police Story 3, before achieving even greater success a few years later with Rumble in the Bronx－a film that not only helped Chan lay down a marker in North America, but established Tong as a renowned action film director.

As an insider who has seen the unprecedented expansion of the film industry on the Chinese mainland in recent decades, Tong says that the idea for Vanguard came to him around 10 years ago, but it was hard to raise such a big budget then.

Now the film, which cost 380 million yuan ($55.6 million), has become one of the widest distributed Jackie Chan films overseas of the past 10 years－and that's just in presale. It proves that action movies are still, arguably, the most lucrative genre to export Chinese stories abroad.

"I hope the film can be developed into a franchise, but that will rely on it not only making a profit in the domestic market, but also performing well in overseas markets," says Tong.

Aside from China, Vanguard will also open simultaneously in seven countries, including Singapore, Malaysia, Thailand and the United Arab Emirates on Saturday, as well as in North America by April or May.