SONNY Bill Williams admits if he knew his rugby tenure would have been this successful, he probably never would have made the handshake agreement that will see him return to the NRL next year. Williams stands on the verge of leaving the game with a clean sweep of major trophies; the World Cup, a Super Rugby title, and if the All Blacks defeat the Wallabies tomorrow night, the Bledisloe Cup. If he does, there will be no wild celebrations. Hours after the game at Eden Park, Williams will catch a flight to Japan and meet his new Panasonic Wildknights teammates in Ota City. The All Black centre will return to league â€“ believed to have been decided upon a handshake agreement with Roosters boss Nick Politis - once his Japanese rugby stint ends in January, but concedes he may have made a different decision in hindsight. "You know when I came here three years ago I didn't even know if I could play rugby,â€ Williams said. â€œI didn't know how the future was going to unfold but it was good to have that security knowing that I had a job in three yearsâ€™ time in rugby league. â€œIf things don't work out over there [Australia] as well as I hope then maybe I might be back here, but who knows what is going to happen? â€œWhen I first came into the All Blacks squad I definitely felt like I didn't belong here, I didn't know anyone. I had come straight from ITM Cup and I felt like I was out of my depth. I was still improving as a rugby player. "After being involved so long, and being involved in  Tests you really appreciate what you have. Now that I understand rugby I have got the utmost respect for it and you kind of look back on it definitely happy knowing you've been able to accomplish what you have. "I've got one hand on that Bledisloe and I want to get both hands before I leave so I've been telling the boys, â€˜send me off with a win brothersâ€™.â€ So is he saying he has to honour a handshake deal but could walk out on a signed contract?