Former heavyweight world champion Wladimir Klitschko has retired from boxing - ruling out a rematch with Britain's Anthony Joshua. The Ukrainian, 41, was knocked out in the 11th round by current champion Joshua at Wembley Stadium in April. Joshua, 27, had hoped Klitschko would sign his rematch clause for a proposed fight in Las Vegas on 11 November.

Just a couple of guys having a chat...

Floyd Mayweather filed a petition July 5 asking the IRS for a reprieve from unpaid taxes from 2015 until after his fight with Conor McGregor in August. "Although the taxpayer has substantial assets, those assets are restricted and primarily illiquid," Mayweather's petition stated, per the legal website Law360 (h/t ESPN.com's Darren Rovell). "The taxpayer has a significant liquidity event scheduled in about 60 days from which he intends to pay the balance of the 2015 tax liability due and outstanding."

Senior figures within amateur boxing have warned many bouts, including those to decide medals, could be fixed at the Olympic Games in Rio de Janeiro amid widespread concern about corruption and financial malpractice at the sport’s global governing body, the Guardian can reveal. Horrified senior officials within the sport believe a cabal of officials are able to use their power to manipulate the draw and the judging system to ensure certain boxers will win.

Comedian Billy Crystal gave one of the best homages to Muhammad Ali at the boxing legend’s memorial service in Kentucky on Friday. Sprinkling the tribute with laugh lines, Crystal described his first meeting with Ali when he was a struggling comedian and discussed their ensuing decades of friendship.

Worshippers and fans of Muhammad Ali are attending a Muslim prayer service to honour the legendary boxer in his hometown of Louisville, Kentucky. The two-day funeral was planned by Ali in the years before his death, according to a family spokesman. Ali wanted the Muslim prayer service, known as a Jenazah, to be "a teaching moment", according to Imam Zaid Shakir, who is leading the service. Muhammad Ali, "The Greatest", died on Friday aged 74.

On February 18th, 1964, just nine days after the Beatles made their acclaimed American debut on The Ed Sullivan Show, and a week before Muhammad Ali (then known as Cassius Clay) won his first World Heavyweight Championship title, these two preeminent cultural forces of the Sixties converged at Miami Beach's 5th Street Gym. What might have devolved into a corny photo-op instead led to some of the most enduring images of the 20th century, capturing the moment these young, charismatic and supremely talented young men achieved total dominance in their respective fields.

Muhammad Ali has died at the age of 74 years old. His death comes after he suffered from respiratory illness. Boxing great, social icon Muhammad Ali dies at 74.

"The Greatest" is gone. Muhammad Ali, equal parts world champion and humanitarian, died late Friday at age 74, a family spokesman said.

Ali was a three-time world heavyweight boxing champion who transcended sports and helped define his turbulent times. He entertained with his mouth as much as his fists, narrating a life of brash self-confidence full of religious, political and social stances.

Muhammad Ali is in "grave condition" in a Phoenix-area hospital, a well-informed source tells NBC News, as the boxing legend continues to battle a respiratory condition.

Former British middleweight champion in induced coma due to bleed on the brain sustained in defeat by Chris Eubank Jr

At 71-0, Bobby Gunn is the king of illicit bare-knuckle boxing. Now 42, he's fighting for something he's never known: recognition. By Stayton Bonner.

The only other person that I had known who possessed a similar charisma to Sunny Balzano’s was my first employer in New York: George Plimpton. Like Sunny, he both stood a head taller than most people and had such a distinctive bearing and manner that in a crowd, one’s eyes would fall on him first and naturally… By Tim Sultan.

“Darrell was already steaming over his split from his girlfriend, and that night, Stan — the better fighter, the better-loved friend, the local boxing hero — also bested him on the dance floor...” By Tim Elfrink.

Nike officially terminated Manny Pacquiao's contract on Wednesday after the Filipino boxing legend described gay people as "worse than animals" in an interview published the day before. The athletic wear giant confirmed the decision to Mashable in a statement, calling Pacquiao's remarks "abhorrent." "We find Manny Pacquiao's comments abhorrent. Nike strongly opposes discrimination of any kind and has a long history of supporting...

Nike said in a statement that it found Manny Pacquiao's comments about same-sex couples "abhorrent" and that it has severed its endorsement ties with the eight-division titlist.

Aggression and masculinity seem so inextricably entwined. I set out to find out why.

Interviews reveal the events in the 60 minutes after a 2013 bout at Madison Square Garden that left Magomed Abdusalamov with severe brain damage. By Dan Barry.