Kampmann got out to an early lead after bloodying Sanchez’ face with punches and stuffing numerous takedowns in the opening round, but fell into a brawl in the second and was rocked late.
Kampmann continued to connect in the third, but Sanchez’ wild combinations and a lone takedown proved to be the difference as Sanchez earned 29-28 scores across the board.
Sanchez (23-4) has now won two-straight since returning to 170-pounds, while the loss was Kampmann’s (17-5) second-straight after dropping a split decision to Jake Shields in October.
In the UFC on Versus 3 co-headliner, Mark Munoz needed just 54-seconds to knockout fellow middleweight CB Dollaway in the opening round, though Dollaway protested the stoppage after appearing to go out only momentarily.
Also on the UFC on Versus 3 main card, middleweight prospect Chris Weidman remained unbeaten with a unanimous decision over veteran Alessio Sakara in his Octagon debut, while former bantamweight champ Brian Bowles returned with a first-round guillotine of Damacio Page, an identical finish down to the time from their first meeting in 2008.
The UFC on Versus 3 prelims included decision wins for Cyrille Diabate over Steve Cantwell and Danny Castillo over Joe Stevenson, while Shane Roller knocked out Thiago Tavares.
The complete results for UFC on Versus 3 were:
MAIN CARD (Versus)
- Diego Sanchez def. Martin Kampmann via unanimous decision (29-28, 29-28, 29-28)
- Mark Munoz def. CB Dollaway via TKO (strikes) – Round 1, 0:54
- Chris Weidman def. Alessio Sakara via unanimous decision (30-27, 30-27, 30-27)
- Brian Bowles def. Damacio Page via submission (guillotine) – Round 1, 3:30
PRELIMINARY CARD (Facebook)
- Cyrille Diabate def. Steve Cantwell via unanimous decision (30-27, 30-25, 30-26)
- Danny Castillo def. Joe Stevenson via unanimous decision (30-27, 29-28, 29-28)
- Shane Roller def. Thiago Tavares via KO (punches) – Round 2, 1:28
- Takeya Mizugaki def. Reuben Duran via split decision (30-27, 27-30, 29-28)
- Dongi Yang def. Rob Kimmons via TKO (strikes) – Round 2, 4:47
- Rousimar Palhares def. Dave Branch via submission (kneebar) – Round 2, 1:44
- Igor Pokrajac def. Todd Brown via TKO (strikes) – Round 1, 5:00
Pictured: Diego Sanchez