Sportal.co.nz 08.Oct.2013Getty Images
Williams added a second NRL title to his impressive list of sporting achievements that already includes an Investec Super Rugby title with the Chiefs and a World Cup win with the All Blacks.
The in-demand 28-year-old must now decide whether to stay in rugby league or return to the 15-man code to play for the Chiefs and All Blacks ahead of the 2015 Rugby World Cup.
Speaking from the Roosters' dressing room on Sunday night, an elated Williams confirmed he would make a call on his future 'in the next couple of weeks' and conceded Sunday's victory makes his decision even harder.
"It's a tough decision coming up ... there's a lot of thinking to be done," he said.
"The last month I asked the club if I could not do any media and just concentrate on my dream and that's winning the competition.
"I just kind of went into my own shell, changed my number, went off social media and just dedicated myself wholeheartedly to the cause and what we were trying to achieve and it's just a dream come true ... I can't stop smiling."
He added when asked if he'll make himself available for New Zealand's Rugby League World Cup campaign in England and Wales starting later this month: "Tonight I'll just savour the moment, be happy with the boys and then I guess in the next week I'll have to sit down and make some tough decisions."
Williams apologised for dodging the media in recent weeks, especially in the lead-up to the grand final, but says he had to eliminate all distractions in order to achieve his end goal.
"These days every little move that I make is portrayed in the media in some sort of way but I just tried to keep a lid on things and just do my own thing and worry about myself and my team-mates and try to get the best out of myself," he said.
"People are different, James Maloney loves that stuff and it seems to bring out the best in them, but me if I just keep it simple and keep a low profile that's when I seem to get the best out of me.
"I apologise for not speaking to the media during the week because it's such a big occasion but as a sportsman I know what gets the best out of me.
"To win a competition like the NRL you have to go that extra mile so I just had to try and do my part."
By his own admission Williams was poor in the first half against the Sea Eagles but he more than made up for his slow start with a match-turning performance after the break.
"I did a bit of study on Manly's left-side defence during the week and Steve Matai and Kieran Foran like to rush up a lot and I was trying to play around them and punch holes around them but it just didn't come off in that first half," he explained.
"At half-time I said to the boys that I'm just going to wipe that first half and go out there and play for them and I expect the same from the boys.
"I didn't want to go back on my word so I just went out there in the second half and tried to run as hard as I could and some good plays came off.
"It just didn't happen in the first half but in the second half I'm proud to say I stood up in the tough times when the game was on the line."