Lesnar wrestled professionally for World Wrestling Entertainment from 2002 to 2004. When he was in the WWE, he won the WWE Championship three times, the King of the Ring tournament in 2002 and the Royal Rumble in 2003. He left the WWE in 2004 and travelled to Japan to wrestle for New Japan Pro Wrestling. While in Japan he won the IWGP Heavyweight Championship. Lesnar retired from professional wrestling to pursue a career in the UFC.