MONTREAL — UFC welterweight champion Georges St-Pierre manhandled Nick Diaz for five rounds en route to a lopsided unanimous decision at UFC 158 on Saturday night.
St-Pierre (24-2) pitched a shutout, winning 50-45 on all three judges' cards.
"Nick Diaz is a good guy," said the champion, looking to end the bad blood between the two.
Diaz, who said he was flat after a 13-month layoff, thanked St-Pierre "for giving him the credit I think I deserve."
Diaz came to the fight with a chip on his shoulder and plenty of attitude. He leaves with a loss and lumps on his face, although he showed the champion respect after the fight.
As expected, St-Pierre used his wrestling to control the chirpy challenger, rag-dolling him at times and bullying him on the ground. But he also used his jab and kicks to pick apart the challenger on his feet.
A calm, calculating St-Pierre won almost every battle during the fight without putting himself in harm's way. Diaz (27-8-0 with one no contest) never quit, but showed less of his trademark trash-talking. He had his hands full.
The main event had been rife with animosity, with Diaz showing St-Pierre little respect. The normally calm champion was red-hot coming into the fight, saying he wanted to "retire" Diaz.
He may have done it. Diaz said his fighting days may be over.
"I think I'm done with this mixed martial arts," he said.
In the lead up to the fight, Diaz skipped a public workout, then put on a strange one-man show at the pre-fight news conference that managed to befuddle and antagonize St-Pierre.
"I never took it personally," the champion said after the fight.
The antagonism continued right up to the fight with fellow fighter Jake Shields, a member of the Diaz entourage, complaining about St-Pierre's hand wraps.
"I checked GSP's glove and the wrap looked shady," Shields, beaten by GSP at UFC 129, tweeted before the fight.
UFC President Dana White said Shields had OK'd the wrap, only to have another member of Diaz's camp complain later.
The 31-year-old from Montreal was looking for his eighth straight successful title defense since winning his 170-pound championship back from Matt Serra at UFC 83 in April 2008. Only middleweight champion Anderson Silva has more title defenses (10).
The welterweight contenders' picture grew clearer earlier in the main card as Jonny Hendricks (15-1) won a unanimous 29-28 decision over Carlos Condit (28-7) in a wild co-main event.