But Shelvey recoiled to supply Michu with a second half equaliser and skipper Williams is confident he will take heart from that and continue to develop as a quality footballer.
"For a 21-year old, he's got balls," Williams told the South Wales Evening Post.
"He isn't shy, and I think for a 21-year old to play how he plays anyway shows he has courage. He is always getting on the ball, he never shies away from it.
"I just said, 'Don't worry about it' to him. I know more than anyone what it's like to make a mistake so I wanted to get him to carry on with the game like normal.
"It happens, we all do that. The important thing is that he was always willing to get on the ball.
"Mistakes stick with you for a little while, but the good thing about football is you've always got a training session.
"The lads have already taken the Mickey out of Jonjo a little bit, but we've got a game Thursday and we've got a game Sunday.
"It won't stay with him for too long, but it hurts at the time."