The two-time winner looked horribly out of sorts against the granite-like Mark King and duly lost 6-3, joining holder and world number one Judd Trump, the well-fancied Mark Allen and former champion Ding Junhui on the list of casualties.
But while the experienced King deserved his win and is no amateur - the experienced Essex cueman improved throughout, knocking in a polished sixth-frame 103 - World Snooker would probably have liked to avoid so many stellar names falling early on.
With Ronnie O'Sullivan taking an extended break from the game, there is a great need for the sport to show it can survive without its biggest draw and, although other stars remain - Neil Robertson was an impressive winner on Monday - there is no denying those to have perished are amongst those many expected to carry the baton in his absence.
"I was terrible. Shocking," Williams, the fifth-best in the world, said.
"I felt all right going in but I couldn't pot three balls on the trot. The table was beautiful, there was a good crowd, everything you could want. It's getting boring for me to say how badly I am playing."
Williams, who lifted the trophy in 2000 and 2003, jokingly suggested he may retire such is how he rates his form, before adding: "I couldn't beat a man with no arms at the minute."
For his part, King, who occupies the last spot in the top 32, was satisfied with his night's work.
"I played pretty solid and you take whatever you can get," he said. "I made a 50-odd and made a century and I'm happy."
Williams is one of the seven players to list the World, UK and Masters titles on his resume, something Australian left-hander Robertson hopes to be able to do come Sunday night.
He sent out a resounding warning of his intentions too, beating Tom Ford 6-1 and cracking in four centuries in the process.
His only slip came when he missed a routine red when on 45 and going for a whitewash, but he was more than happy to finish up with scores of 129, 112, 100 and 127.
"I felt mega-confident today [Monday]," Robertson said.
"Practice has been going very well and I've got a good record against Tom. When I have played him previously I think it's been 6-0 and 6-1 and I knew if I could get on top of him early on then it would be tough for him."
Robertson was speaking before Williams' defeat, but does not think his mission is any easier owing to the list of casualties.
"There are still some great players left in the tournament," said the Victorian, who will next face Barry Hawkins.
"But for me, it would be fantastic to hold the Masters and win the UK, that would be a special feeling. I have the opportunity to do that and to win all three in a short space of time would be great."
While one Welsh former winner went home in the shape of Williams, another went through with Matthew Stevens, victorious in 2003, getting the better of fellow countryman Dominic Dale 6-1.
By his own admission Stevens has not been on song this year, but was given a leg-up by Dale's struggle with what he thinks may be an outbreak of shingles.
The 40-year-old was unable to see a doctor before his match started so played on, lost, and then headed off for a diagnosis.
"He doesn't look the best when he's well, but he looked awful!" said Stevens, who now plays Marco Fu.
"It was one of those unfortunate things. I felt for him as he didn't look well but it was nice to get the win."
The final match to finish on Monday was won by Luca Brecel.
The young Belgian battled for a 6-5 win over Ricky Walden.