Ludwig was trained by
Bas Rutten during his early career. Although not an official title match, Ludwig nonetheless beat Jens Pulver, who was at the time ranked as the #1 Lightweight mixed martial artist in the world by many outlets, by first round K.O.
UFC At UFC 42, Duane Ludwig fought Genki Sudo. Sudo showed his theatrical side, walking backwards towards Ludwig and doing the robot dance before taking him down. Despite the initial domination by Sudo, Ludwig started inflicting damage while standing, avoiding a rolling kneebar and several takedown attempts. Whilst it seemed the momentum had shifted in Ludwig's favor, Sudo came back in the third round and took him down, pounding and bloodying him with punches and elbows. Whilst Ludwig was mounted, referee John McCarthy interrupted and stood the two fighters up. The "doctor's check" allowed Ludwig time to recuperate, while being administered first aid to stop the bleeding in his nose. When the doctor allowed the fight to resume they did not restart from the same previous dominant position held by Sudo. Ludwig took advantage of the indirect rest given to him and avoided the ground and dominated the standup with several hurtful shots on Sudo to win a split decision. Ludwig mocked Sudo after the final bell with a crane kick pose. This eventually led to a rule change that during a doctor's check, fighters will resume the action from the same position where it was halted.
Notorious fast knockout At
UFC Fight Night 3, Ludwig faced
Jonathan Goulet. Ludwig won the fight via quick knockout, though many fans disagreed with the timekeeping of the finish, which was 11 seconds despite the referee pulling Ludwig away from Goulet at around the 6 second mark. Following multiple online campaigns to overturn the timekeeping error, on Christmas Eve 2011, UFC President
Dana White informed Ludwig that he was being given the official fastest knockout time. In 2019,
Jorge Masvidal beat Ludwig's time with a knockout in five seconds.
Return To UFC On December 17, it was announced that Ludwig was set to return to the UFC at
UFC 108, facing
Jim Miller, replacing an injured
Sean Sherk. He lost to Miller via armbar in the first round. Ludwig was scheduled to face
Spencer Fisher on March 21, 2010, at
UFC LIVE: Vera vs. Jones, but Fisher was forced off the card with an injury. Ludwig instead faced UFC newcomer
Darren Elkins. Ludwig lost via TKO after he suffered a serious ankle injury during the first round. Ludwig moved up to the Welterweight Division to face
Nick Osipczak on November 13, 2010, at
UFC 122. The fight was supposed to be on the preliminary part of the event, but a last minute illness to main card fighter
Alessio Sakara moved the bout to the main card. Ludwig scored with strikes, including multiple grazing headkicks in the first round until Osipczak landed a combination, buckling the veteran. The round ended with Osipczak landing ground and pound from the top, bloodying Ludwig. The second round was pretty even with mixed striking exchanges and takedown attempts. The third round saw Ludwig land a big left early on and basically stalk Osipczak the rest of the round, scoring but failing to finish as Osipczak was seemingly out on his feet, walking away from exchanges and covering up. The bout was Ludwig's first since an eight-month recovery from a severe leg injury. Ludwig won by split decision. Ludwig was expected to face
Amir Sadollah on March 26, 2011, at
UFC Fight Night 24, but was unable to fight due to a sternum injury.
James Wilks took his place in the match instead. Ludwig vs. Sadollah eventually took place on August 14, 2011, at
UFC on Versus 5. Ludwig won the fight via unanimous decision (29-28, 29–28, 29–28). Ludwig outstruck and rocked Sadollah in both the first and second rounds while also showing greatly improved takedown defense throughout the fight. Ludwig next faced
Josh Neer on January 20, 2012, at
UFC on FX: Guillard vs. Miller. Despite hurting Neer on several occasions via punches, Ludwig lost the fight via technical submission in the first round. Ludwig fought
Dan Hardy on May 26, 2012, at
UFC 146. Ludwig suffered a knockout loss to Hardy when he was hit by a flush left hook and followed up elbows. Ludwig faced
Che Mills on September 29, 2012, at
UFC on Fuel TV 5. The bout was stopped after Ludwig was unable to continue after tearing a knee ligament while attempting to defend a takedown in the opening round. After his loss to Mills, Ludwig retired from MMA competition. From December 2012 to May 2014, Ludwig was the head coach at
Team Alpha Male. Ludwig left Team Alpha Male after
UFC 173 to focus on growing his own gym, BANG Muay Thai. ==Personal life==