The British number one finished first in the Hickstead Master's Challenge, and second in the Bunn Leisure Derby Trial, to take home a paycheque of £5,500.
The 39-year-old rider from Kent won the afternoon's feature class on board the Chestnut gelding Titus, finishing clear in a time of 47.18 sec. Shane Breen (Magic Fox) and Nick Charles (Murka's Midnightlady) were both very close on Guy's heels - finishing on the exact same time of 47.83 to finish second equal.
Guy is feeling confident ahead of the Carpetright Derby, and is pleased with how Skip Two Ramiro - whom he rode in the Bunn Leisure Derby Trial - and his other horses are all going.
"Titus has won every single class he has been entered into, winning six classes in the past two weeks," said Guy.
Just 0.22 of a second kept Guy Williams off top spot in the Bunn Leisure Derby trial, with the spoils going to Peter Charles (Murka's Vindicat W).
Despite winning the Derby Trial, Peter will not be riding the nine-year-old gelding in Sunday's Carpetright Derby.
"I'd love to jump him in the Derby, and I think he will be a winner of the class in the future, but I'm going to give him one more year's preparation," he said.