After a long spell with the NRL's Canterbury Bulldogs, and considerably shorter ones with rugby's Toulon, Canterbury and Crusaders, he's on the verge of another new season, with another new team.
He has a one-year contract with the Chiefs and will probably return to Sydney to play league next year. Reports of a breakfast meeting in Circular Quay, Sydney, with Roosters chairman Nick Politis and Channel Nine boss David Gyngell did little to quell belief he will soon return to the NRL.
But before all that, on Wednesday night in Hamilton, Williams will fight Clarence Tillman III for the vacant New Zealand heavyweight title.
His opponent can't win it. He's American, and was a late replacement for original opponent Richard Tutaki who was dumped after it emerged he faced serious drugs charges.
That's Williams, whose face, and impeccable physique are used to advertise everything from sporting attire to energy drinks. Many companies are so keen to have him endorse their products it can become the source of conflict, like the one that surfaced with his plans to endorse a competitor to one of their own brands.
But of Nasser? Not so much is known. And that's the way he wants it to stay.
Approached at a media session called to promote Wednesday's bout, Nasser declined.
"Mate, if I give you an interview, everyone will want one and I'll get smashed," he said. "Smashed. It's all about the show there," he added, pointing to Williams who was beginning a training session in the ring.
Williams, too, was reticent, preferring to reveal his six-pack over his thoughts on his manager.
Asked whether Nasser was an interesting character, Williams said only: "Very interesting. He's his own man. He's a good bloke."
When it was suggested that the kind of athlete/manager relationship seemed unusual in the sporting world, Williams added: "It probably wouldn't work for everyone, but it works for me. Things have gone pretty good so far and I'd like to keep it that way, hopefully."
It was hardly a ringing endorsement, but Williams - and Nasser - delight in keeping people guessing.
Nasser is unorthodox but gets results. The other sportsmen he represents - former league player turned light middleweight boxing champion Anthony Mundine, and Wallabies first five-eighths Quade Cooper - are just as polarising.
He was accused of exploiting Williams and persuading him to leave the Bulldogs soon after he signed a big-money deal due to a personal campaign against the club.
It has been reported Mundine paid A$750,000 on behalf of Williams to settle the contract row with the Bulldogs, but another school of thought suggests Nasser dipped into his own pocket - which is why the 26-year-old is so loyal to him.
Cooper's decision last year to join Nasser's stable raised more than a few eyebrows in the genteel world of Australian rugby.
To say the trio are his clients, though, could be overstating the case. He hasn't signed contracts with any of them.
"If they're not happy with me, why should they stay with me?" Nasser has told journalists.
It is said that he doesn't own a computer. He certainly doesn't employ any staff to help with administration. The multimillion-dollar operation is all run by a sharp business brain and ruthless negotiating style.
"The thing that I love about Khoder is that he's ruthless," Mundine told the Sydney Morning Herald in 2010.
"His No1 priority is his client and getting the best deal for the person he represents. He doesn't care if he pisses people off. In fact, I think he loves it."
Nasser has his roots in Tripoli. His grandfather moved from the Lebanese city to Sydney in 1950 and, according to the SMH, worked in a factory for 11 years before he had enough money for his family to join him.
Nasser told the newspaper even growing up as a second-generation immigrant, he felt like an outsider.
He graduated from Wollongong University with a bachelor of arts, majoring in economics and politics, but dropped out of a teaching master's degree at Sydney University.
A devout Muslim, he famously met Mundine at the Sydney Cricket Ground in the 1990s and they clicked instantly (like Williams, Mundine has converted to Islam).
Managing Mundine was a role he fell into. At the time his work experience consisted of working at a pharmacy and a cafe.
Nasser was certainly a new experience for the NZRU, who are more used to dealing with the traditional agent, someone with a background in commerce and law. Most have several players on their books.
Chief executive Steve Tew has said Nasser is great to deal with because he is straightforward with no hidden agendas. But Nasser is so hands-on it is understood he demanded to know why Williams had been "dropped" to the reserves by Canterbury and had to be placated by coach Rob Penney in a busy Christchurch cafe.
He makes no apologies for making big decisions on behalf of Williams, Mundine and Cooper, saying it leaves them to concentrate on what they do best.
Cooper told the Brisbane Times: "The good thing about him is he tells it how it is. He's not there to talk you up and tell you lies about how good you are or how good you aren't.
"It's all about trust. I don't see him as a colleague, I see him as a mate. If you've got trust there, that's enough for me."
Nasser is big on respect and loyalty and is known to go from fury to charm in the space of a phone call.
He doesn't do flashy, preferring modest clothes and an ordinary car. This week in Hamilton he was carrying a Chiefs-branded backpack.
He is married with children, the family home near his parents in Sydney. He is a fan of all sports - cricket, union, league, boxing, tennis.
But his favourite? It happens to be soccer. But not just any soccer. Teams who attack, who entertain. And his sporting hero? It is said to be Zinedine Zidane, the former France midfielder whose last act in an illustrious career was to headbutt an opponent in a World Cup final. "It's about putting on a show," Nasser says. "I love Brazil, Argentina, teams like that."
The show. It could only ever be about the show.
