No longer possessing the skill, stamina or desire for boxing, Mike Tyson says he is quitting the sport to become a missionary.

Tyson put on a disgraceful performance against unheralded Irishman Kevin McBride on Saturday night, losing on a technical knockout after refusing to come out for the seventh round.

"I just don't have this in my gut anymore," Tyson told reporters after the fight. "I wasn't really interested...It's just not in my heart anymore. It's hard for me to fight."

A frustrated and fading Tyson tried to break McBride's arm during a clinch in the sixth round and then attempted a vicious head-butt in an outrageous effort to end the fight.

"I was desperate, man. I wanted to win," Tyson said.

The round ended with Tyson on the canvas, not from a knockdown but from a push. But the former champion was out of gas and staggered back to his corner like a man on a two-day drinking binge.

"I was tired. I didn't want to get up," Tyson said.

Tyson's handlers told referee Joe Cortez that their boxer was unable to continue.

Also Read Tyson falls to McBride Tyson weighs in at 233 for McBride fight I will gut McBride like a fish, says Tyson

"His equilibrium was shot and he was trying to get up and he couldn't," said McBride's trainer, Goody Petronelli. "And if he did get up, he would have really been hurt. I think the corner made a wise decision to throw in the towel."

Tyson, 38, who still owes millions to creditors despite his $5 million payday, said he wanted to change his life.

"I'm going to look into my missionary work," Tyson said of his post-boxing plans. "There is some Christian missionary work that was interested in letting me come to Bosnia, go to Rwanda, go to different countries to help with aid and food for people that are in dire need."

MISERABLE

Tyson looked terrible in a fourth-round knockout loss to little-known Briton Danny Williams last year and looked equally miserable against McBride, a 32-year-old journeyman.

"I could beat everyone but I just couldn't beat Father Time," said Tyson. "I lack the discipline and desire to do this stuff anymore."

Tyson has been a professional fighter for two decades and in 1986 became the youngest champion of all-time at 20 years old.

He acknowledged, however, the last 15 years was somewhat of a sham, saying his career "has been over since 1990".

Despite a 33-4-1 record with 28 knockouts, McBride was without a significant victory until the Tyson fight. He said he was ready to fight World Boxing Council champion Vitali Klitschko, his brother Wladimir, or any other top contender.

"Mike Tyson is a warrior and he's one of the greatest champions of all time," McBride said. "Let's get the Klitchkos and knock them out and whoever else wants to fight.

"You want to be the best you've got to beat the best. I'm a contender, not a pretender."

Tyson, who closes his career with a record of 50-6 with 44 knockouts, received a pre-fight pep talk from Muhammad Ali, who was among the 15,472 in the crowd at the MCI Center.

But even the three-times champion could not light a spark and make up for Tyson's deteriorated skills.