In addition, while touring Japan regularly, he faced top American wrestlers including Andre the Giant, Dusty Rhodes, Bob Backlund, and Hulk Hogan. Hansen established himself as a dominant force in Japan by competing in New Japan's MSG (Madison Square Garden) tournament between 1978 and 1981. Hansen would win the NWF World Title from Antonio Inoki on February 8, 1980, one of the only two wrestlers to dethrone Inoki during his seven-year reign. From November 21 to December 13, 1980, Hansen did a tour for NJPW, where he competed in the first MSG Tag League tournament (later renamed the G1 Tag League). He teamed with Hulk Hogan, but they failed to win. He returned that April to wrestle Antonio Inoki in an unsuccessful match. However, he defeated Hansen via countout in a MSG League match in May 20, 1981 after hitting a lariat on Inoki, knocking him off the apron. He returned for several more one off shows until leaving the promotion in December 1981. Hansen returned at NJPW's Super Fight In Tokyo Dome event in 1990, where he had an infamous interpromotional match against Vader. The match for the IWGP Heavyweight Championship saw Big Van Vader (representing New Japan, while Hansen represented All Japan) get struck in the eye during the entrances by Hansen's Bullrope. Both men were known to use a stiff style of wrestling, resulting in a nasty exchange where each man threw legitimate punches. The match ended in a draw. He returned in June for a few more matches, teaming twice with Riki Choshu and once with The Pegasus Kid. In 1981, Hansen abruptly left NJPW to join All Japan Pro Wrestling (AJPW). While in AJPW, Hansen became the only man to pin Antonio Inoki and Giant Baba in championship singles matches. He continued wrestling from 1982 to 1999 in World's Strongest Tag Determination League. He wrestled primarily in tag matches, where he formed many teams with the likes of Bruiser Brody, Terry Gordy, Ted DiBiase, Genichiro Tenryu, Dan Spivey, Bobby Duncum Jr., and Big Van Vader. Hansen also engaged in a renowned brawl with André the Giant in Japan. In addition to championship matches, Hansen also competed in other high-profile matches. At the NJPW Super Fight in Tokyo Dome show on February 2, 1990, Hansen competed in another notable match as he represented AJPW against NJPW representative Big Van Vader.