Williamson took Pembrook Playboy back to the stables of Andrew and Lyn Neal where his team was staying and was certain the season was done.
"But when I let him go in the paddock he was still full of himself, which really surprised me," he explains.
Knowing the $40,000 Uncut Gems races were still available to horses who hadn't placed at the Jewels nor won a race worth more than $55,000, Williamson had a think then made a phone call to cancel Pembrook Playboy's transporter home.
"I had a hunch and when I worked him a few days later it made me think I was right, he was far better than he has been heading to Jewels Day.
"I think what happened was he didn't travel well and so I eased up on him and then they have gone 1:51.6 for the mile at the Jewels and he just wasn't ready. He wasn't fit enough.
"But he has turned the corner, with both the run under his belt and feeling better and his work this week has been exceptional."
Pembrook Playboy will need to be close to his peak to win the Uncut Gems male pace in which he has drawn the outside of the second line on what will be his Alexandra Park debut.
"I am not saying it will be easy but it looks like a front line where they could go hard and that might pan out well for us.
"If they do that will suit him and he will be hard to beat."
The field has genuine depth though with Dance Time in career-best form, Fabrizio talented albeit it annoying for punters, and Steel The Show and the returning Double Rocket proven at group race level.
While Pembrook Playboy's work since the Jewels has boosted Williamson's confidence ahead of Friday night, a slight setback to a stablemate may have increased the southern horseman's chance of driving the winner of the $40,000 Uncut Gems Trot.
Williamson was forced to scratch Kiwitrix because of a setback which means he can drive Credit Master, trained by the Neals, in the standing start 2700m.
"I drove him when he won last start and he has to be hard to beat this week, although Midnight Dash looks a logical danger."
Williamson also rates his upset chances in the $40,000 mares race even though Pearl Harbour (R6, No11) was disappointing to the eye after trailing in her division of the Jewels.
"She might have trailed but she had to work hard to hold the lead before that and that isn't her go," he explains. "If she can get the right suck into the race this week you might see a different horse."
That Gem has a South Island feel to it with Folklore superb in her two runs in the north, Tres Chic an Alexandra Park newcomer with outstanding form and Cheezel up to most of her northern rivals.
Five to back
See Fire (R3, No4): Hung terribly and still bolted in last start, suggesting he has an open class motor. If he trots all the way, should clean these up.
Hot and Treacherous (R7, No6): Phenomenal in the 3-y-o boys Jewels after being three wide the last lap. Meets some classy opposition but has developed into a good horse.
Midnight Dash (R4, No7): Has been good to very good in open class races this season, was fourth in super strong Jewels and looks ideally suited tonight.
Folklore (R6, No7): Two booming runs in the north and has the crucial advantage of Alexandra Park experience over key rival Tres Chic.
Pembrook Playboy (R8, No11): Not an easy race but he is a NZ Cup horse later this year and the trainer is confident he is returning to something like his best. All he needs is the right cart into the race.
Michael Guerin