Answer by taking a quote from the following article:

Yen was born in Guangzhou, China. His mother, Bow-sim Mark, is a Fu Style Wudangquan (internal martial arts) and Tai Chi grandmaster, while his father, Klyster Yen (Zhen Yun Long ), is a newspaper editor. When he was two years old, his family moved to Hong Kong and then to Boston when he was 11. His younger sister, Chris Yen, is also a martial artist and actress, and appeared in the 2007 film Adventures of Johnny Tao: Rock Around the Dragon.

Donnie Yen was a rebel when he was young due to the huge expectations and pressures from his parents, as his mother is the founder of the Chinese Wushu Research Institute in Boston, and his father was a scholar and a musician. Yen joined a Chinatown gang in Boston, MA, in his early years. He was a very curious teenager who sought to exchange martial arts knowledge with people from different martial arts backgrounds, which led to him gaining profound knowledge in practical martial arts and having a reputation as a street brawler.  One reported occasion confirms Yen as being an efficient martial artist. According to news reports by Hong Kong news channels in the late 1990s, Yen was at a nightclub with his then girlfriend, Joey Meng. Inside the nightclub, Joey was harassed by a troublesome gang that had taken an interest in her. Yen warned them to leave her alone, but they persisted to cause trouble. As Yen and Joey left the club, the gang followed and attacked Yen. Yen beat up eight members of the gang who were later hospitalized.  Malaysian Martial Arts Star Michelle Yeoh has said that Donnie Yen is the fastest guy she has worked with. Other martial arts stars such as Jackie Chan and Jet Li have also stated that Yen may be the best fighter in terms of practical combat in the Asian cinematic universe.  World class fighters, such as former Strikeforce Middleweight Champion Cung Le and former World Boxing Heavyweight Champion Mike Tyson, who have worked with Donnie Yen in the films Bodyguards and Assassins and Ip Man 3, respectively, have both claimed that Donnie Yen is an incredible martial artist and would do well in authentic combat. While filming Ip Man 3, crew members were afraid that Mike Tyson, who had been a professional boxer, would forget the choreography and throw real punches to injure Yen. However, it was ultimately Yen who fractured Tyson's finger while using his elbow to block Tyson's punches.

What was is prowess?