O'Neill told Villa's website: "It must have come to him very quickly because he couldn't adjust. It just hit him and went into the net."
Looking at Sidwell's overall contribution, he added: "He's got into the side, he can get a few challenges in and get forward. I was really pleased with him. I think he's capable of scoring a few goals.
"Obviously we've got to try and play him in that role where he can maybe get forward to do that. But we've got lots still to do, lots to figure out how best to utilise it at this moment.
"It's just his general play, I think he can improve all round. First of all he hasn't played for basically a year, he's been in and out.
"I'm hoping that if we can get strong enough that everybody's really fighting for positions here. He's got a bit of athleticism and can get up and down, but we'll see. I was very pleased with him."