SACRAMENTO, Calif. >> UFC welterweight champion Georges St. Pierre vacated his title today, citing a desire for a lengthy break from mixed martial arts.

St. Pierre believes he’ll eventually return to the sport, but doesn’t want to block other fighters’ advancement in the welterweight division while he takes a break from the relentless pressure of training and sorts out unspecified personal problems.

"I can’t hold on to my title for the respect of the other competitors," St. Pierre said. "One day when I feel like it, I might come back, but right now I need a break."

The Canadian star has been the UFC’s 170-pound champion for nearly six years, winning 12 straight fights with nine consecutive title defenses. He beat Johny Hendricks by split decision last month at UFC 167 in Las Vegas.

"I never felt better physically," St. Pierre said. "For me, it’s mental. It’s a lot of pressure. For me in order to keep my mental equilibrium, for me emotionally, I need this. I need to have a normal life for a bit, and I’ll feel better and come back stronger."

Hendricks will fight Robbie Lawler on March 15 in Dallas for the vacant welterweight title, UFC President Dana White said.

The 32-year-old St. Pierre (25-2) has been generally considered the UFC’s biggest pay-per-view draw since the departure of heavyweight Brock Lesnar, defeating every challenger in the welterweight division with superb technical skill.

But St. Pierre has lamented the stress of his prominence in the sport, saying his obsessive nature prevents him from enjoying life while maintaining the focus necessary to train for title fights.

"It’s been a long time I wanted to do this," St. Pierre said of his break. "It built up on my shoulders, training camp after training camp. I have personal things I want to do. My life is a … zoo right now. I need to take a break. I’ve been fighting a very long time on a high level."

Although St. Pierre’s departure deprives the UFC of one of its most accomplished champions, White praised the decision, saying he would never pressure a fighter to stay too long in the sport.

"This is fighting, and you have to be 100 percent mental, physical," White said. "And if you’re not, you should sit on the sidelines until you get back. I think this is the right move for Georges St. Pierre. You can hear by listening to him he’s got a lot of issues personally he needs to deal with."

St. Pierre hasn’t lost since April 2007 when Matt Serra took away the 170-pound belt. St. Pierre reclaimed the title later that year and beat Serra in a rematch shortly afterward.

But St. Pierre didn’t fight between April 2011 and November 2012 while recovering from a torn ligament in his right knee. He has bounced back from injury with wins over Carlos Condit, Nick Diaz and Hendricks, although his most recent victory was widely debated.

St. Pierre took extensive facial damage in his fight with Hendricks, but claimed injuries and the overall physical toll of fighting had nothing to do with his hiatus.

"I believe one day I will come back," St. Pierre said. "The problem is I don’t know how long. I can’t put myself through another training camp right now. I feel like mentally I need a break, and I don’t want to make nobody wait. It has to be up to me. It has to be on my terms, and when I come back, I will come back stronger."

Hendricks, a NCAA champion wrestler at Oklahoma State, has been the division’s top contender for several months, and White was among the ringside observers who thought he beat St. Pierre last month. Lawler has risen to title contention with three straight victories after dropping from middleweight to welterweight.

The fight will be held at UFC 171 at American Airlines Center in Dallas on a card originally slated to feature light heavyweight champion Jon Jones’ defense against Glover Teixeira. That fight has been moved to UFC 172, although that card’s location and date haven’t been set.