The 27-year-old former All Blacks centre, who has had six professional boxing fights, helped to attract a bumper crowd of 35,952 to the Sydney Football Stadium for his Sydney Roosters debut against the South Sydney Rabbitohs in the opening match of the National Rugby League (NRL) season.
It was not a winning start for Williams, though, and his try five minutes from time was little more than a consolation as the Rabbitohs, part-owned by Hollywood actor Russell Crowe, ran out convincing 28-10 winners.
"Maybe people were expecting me to work some magic," Williams told a local television station.
"For me, it's about concentrating on the little things and doing my job well.
"There's a few things that I was bit rusty on but it's a start."
More than a century of fierce rivalry between the clubs ensured the match would not just be about the Roosters number 16, whatever the ubiquitous television advertising campaign running all month with its tagline "SBW OMG" might have suggested.
There was clearly some relief in the league heartland of New South Wales that the action on the pitch was finally underway after a pre-season dominated by an anti-doping investigation into the use of banned substances in the sport.
There has been great excitement at the return of a player with genuine international profile to the sport he controversially abandoned to go and play union in France in 2008.
"It's been very much across the board too," Talking NRL radio show host Mark Pannowitz told Reuters.
"It's not just been the Roosters fans, Sonny Bill makes the game easy to sell; he's the sort of player who, as they say, puts bums on seats."
Most of the fans at the Sydney stadium were on their feet after half an hour of Thursday's contest when Williams, who had started on the bench, took to the pitch with his team 10-4 down.
"Sonny! Sonny! Sonny!" chanted the Roosters faithful but there were boos too, some from the Rabbitohs fans and others from a small group in the colours of the Canterbury Bulldogs, the club Williams left 18 months into a five-year contract in 2008.
"SBW we will never forget" read the banner they held aloft - a reminder of how divisive the New Zealander's determination to plough his own furrow in his sporting career has sometimes been.
It took three tacklers to drag him down on his first possession, and his second ended with the trademark offload which he brought so effectively to union with the World Cup-winning All Blacks and Super Rugby champion Waikato Chiefs.
Ultimately, though, the Bondi-based Roosters were second best to a mobile South Sydney side, for whom prolific winger Nathan Merritt snared a hat-trick and Englishman George Burgess scored a try on debut.
"It's going to take a lot more than Sonny Bill to win a Premiership but he will help them get better," Pannowitz said.
"He does look a little bit off the pace. I'd say he was about 60 percent of the player he was when he left.
"When he left he was devastating, one of the best players to take on the line that the game has seen for a long time. He always got the ball away." (Editing by Clare Fallon)