Williams was not meant to race in the men's sit-down slalom until later in the week, but had his races moved forward as a result of heavy weather disrupting other events.
In his first run, Williams was 25th of 42 finishers in 57.38sec .
However, as the day wore on and weather delayed the second run, the slopes cut up and the majority of competitors were actually slower in their second turn.
Williams finished his second race up the order, but in a slower time, for a combined time of 2min 05.55sec.
His overall result put him at 22nd after his two races.
The event was won by German Martin Braxenthaler in a combined time of 1min 41.63sec.
"It was great to get a feel of the slopes.
"I was relatively happy after the first run and really wanted to step it up in the second, but the conditions were tough and I was [starting] towards the end.
"It was really rutty out there and the visibility was limited," said Williams (24), from Auckland, who has spina bifida and is competing in his first Winter Paralympic Games.
"The second run was slower as a result of the slope getting really cut up.
"Most of the field were slower.
"Aside from today's race the organisation of the games has been an incredible experience so far and something I'll never forget," he said.
He races in the super G tomorrow and said he was ready to just "go for it".
Dunedin's Adam Hall takes to the slopes for the standing slalom today, weather permitting, and has been ranked as one of the world's best in his event.
