However, Williams was forced off with a hand injury midway through the first half and centre King left the field on a stretcher after suffering a facial injury in the closing seconds of the cup encounter.
Stanley admitted Warriors would now need to wait on the outcome of medical checks, but did praise young scrum half Joel Dudley for impressing after he took the spot of Williams.
"Greg (King) has taken a knock on the face and has gone to hospital for pre-cautionary x-rays," said Stanley.
"We will know more in the coming days, but at the moment the picture of what he has done is unclear. He was lucid when he came off and talking, so in that respect he is okay.
"Andy (Williams) has got a bang on the hand and has also gone to hospital for an x-ray to see how that is.
"Joel Dudley came on and did very well in his place. It was only his second game for the senior side and he has not had a lot of rugby this year with us.
"Full credit to him for both this week and last weekend and grabbing the opportunity when it arose.
"He scampered away for that one break and is a quick boy. He works very hard and I'm glad he has been given an opportunity."