"It feels a little bit uncomfortable at the minute", he laughed.
It's an unbelievable story really.
It capped a remarkable late-career revival as he did not even qualify for the championships in 2017, and last reached the final 15 years ago, when he defeated Ken Doherty.
"But for him to do that, I can only imagine what he went through, coming back every year and going again".
He told the crowd "As long as Barry Hearn is not going to fine me or discipline me, I'll have to do it". What an advert for the sport.
In a dramatic 33rd frame, Williams made 63 before missing match-ball pink to a corner pocket. If I never win another tournament, I don't care now.
"I just can't believe it".
Higgins looked down and out when he trailed 14-7 after Williams reeled off the first four frames... The Welshman, however, held his nerve in the next frame, a break of 69 taking him over the line.
Scotsman Higgins has not been at his best in this final and despite battling valiantly against his old foe, he had yet to win a session over the first three sessions until the final session when he has produced breaks of 131, 67, 82 and 62 to win the first five frames. Wife Jo was seriously ill at one stage earlier in the season but she too watched on in Sheffield.
Last time he won Williams said he "had half a pint of milk and went to bed".
"I'm sure they've enjoyed it". I was still upbeat about my game and then luckily it changed round and Mark missed a few times at 50 or 60 in front and I managed to clear up and that got me back in the game. I thought these sort of days had passed for me.
Williams held his nerve and landed a title that he himself saw as a massive ask only a year ago, when he told reporters that he would strip off in the press conference should he win the trophy. The two-time former world champion from Wales recharged his batteries with a couple of hours sleep to return to the table to get the upper hand over Scotland's Higgins on Sunday. "The break in the last frame was one of the best I've made under pressure in my life".
"Today I was 13-7 behind and I was anxious if I would take it to the fourth session, I didn't want to lose with a session to spare".
All the momentum was with Higgins, who had won six of the last seven frames, and Williams desperately needed to halt the charging Scot.