Williams headed home a perfect delivery from Jordi Gomez with fifteen minutes to go to rescue a point for the Swans as they looked to be heading for a night of frustration at the Liberty.
Williams managed a rare Swansea shot on target as they dominated posession but lacked the killer touch to finish off an average looking Derby side.
It was only the fourth goal of Williams' career and his first in Swansea colours but the club record signing admitted that he would be targetting more "It was very pleasing for me
"I've come close in the last few weeks so it was nice to score on the night.
"I don't really score many goals but I always come quite close, it's something I'd like to put right this season and try and get a few more goals."
Roberto echoed the words of his defender "He's been around that area for a long time," he said.
"He's had a few headers, his movement and the delivery from Jordi Gomez was something special and it's something for him to keep working on what is another step into this division."