Jet Li's 2001 sci-fi movie The One pit him against a version of himself from another universe, and used different Chinese martial arts forms to capture the hero and villain's personalities. The One debuted during Jet Li's early rise to fame in Hollywood. Already one of the biggest stars in Hong Kong action movies, Li's appearance as the villainous Wah Sing-ku in 1998's Lethal Weapon 4 kickstarted his stateside career.
Li subsequently led the action films Romeo Must Die and Kiss of the Dragon, with The One being his first PG-13 Hollywood movie. In The One, Li plays Gabriel Yulaw, a former cop for the Multiverse Agency on a mission to assassinate his parallel selves across the Multiverse in order to absorb their energy. In doing so, Yulaw seeks to become an all-powerful being known as "The One." Having eliminating 123 out of 124 of his alternate selves throughout the vast Multiverse, Yulaw's final target is LAPD cop Gabe Law, both of them possessing superhuman strength and speed as a result of Yulaw's killing spree.
While both Gabe and Yulaw are very skilled martial artists, each practices a distinctly different form of kung fu. Gabe is an opponent of Baquazhang ("Eight-Trigram Palm"), while Yulaw is a practitioner of Xingyiquan ("Shape-Intent Fist"). This was a very specific choice on the part of the makers of The One, including Li's longtime collaborator Corey Yuen, who served as fight choreographer. In having Gabe and Yulaw utilize their respective martial arts, this was intended to reflect their individual mindsets as people.
Baquazhang is characterized by elusive, circular footwork and open-palm strikes, with the practitioner evading and countering attacks with their flowing movements. Avatar: The Last Airbender would later uses Baquazhang as the basis for Waterbending. The nature of Baquazhang reflects Gabe's belief, articulated to Multiverse agent Fusch (Jason Statham), that "the energy of life goes in a circle, in a perfect flow, balanced," and the need to find one's center. In his quest to become The One, Yulaw has a totally different outlook on life. Conversely, Xingyiquan is a very linear martial art, with aggressive and direct punching and reliance on explosive power, or "fa jing". This captures the essence of Yulaw's determination to become The One. With that as his singular goal, he's focused completely on that to the exclusion of everything else, letting nothing stand in his way until he achieves it.
In its original conception, The One was almost a completely different movie altogether. Dwayne Johnson was originally in The One, attached in the dual hero-villain role, with Johnson at the time making his transition from pro-wrestling to movies. In that version of the film, his two character's fighting styles were "more street-brawl kind of fighting," per visual effects supervisor Eric Durst in the documentary "Multiverses Create The One" on The One DVD. Following Johnson's departure, Li's boarding gave Gabe and Yulaw's fighting styles a major Wushu makeover.
Over two decades since The One's release, the Multiverse is rapidly being re-popularized on the big and small screens. Both DC and Marvel's superhero films and shows are heavily diving into their multiverses. A24's Everything Everywhere All At Once also using the Multiverse as its basis with Michelle Yeoh anchoring the film. Jet Li has shifted his focus primarily to philanthropy in the last few years, but the legacy he's left on the martial arts genre cannot be overstated. The One is strong testimony to that, using two different kung fu forms to create a Jet Li martial arts showdown that genuinely stands alone.