The kick was damaging, as seen in this shot, and sent Diaz to the ground.
Thomson's strikes after the headkick were so damaging that Diaz's corner threw a towel into the cage as referee Mike Beltran stopped the bout.
Though Diaz has lost decisions n his UFC career, this is the first time he was stopped since 2006. It's his second loss in a row, as he dropped a title fight to Benson Henderson in December. Diaz talked about moving back to welterweight from lightweight after this bout, which appears to be a viable move.
Before this fight, Thomson's last bout was a loss to Strikeforce champ Gilbert Melendez. Thomson has struggled with injuries, but when he's healthy, he can do things like knock out Diaz.
In earlier action, Matt Brown continued an impressive run by withstanding Jordan Mein's attacks and scoring a TKO in the second round. Brown is on a five-fight win streak, with four of those wins coming by knockout or technical knockout.
Other popular content on Yahoo! Sports:
• Images from the manhunt, capture of Boston bombing suspect
• Texas A&M quarterback Johnny Manziel is ready for his encore
• Ball Don't Lie Power Rankings: First-round NBA playoff matchups
• David Ortiz punctuates Red Sox pregame with strong statement
- Sports & Recreation
- Martial Arts
- Nate Diaz
- Josh Thomson