Rhys Patchell kicked 14 points in his country's victory over Australia after coming on as a substitute.
It means Wales are one step closer to a place in the quarter finals of the Rugby World Cup in Japan.
"I was extremely nervous," mum Eleanor told BBC Radio Wales. "I didn't see it.
"I had prepared all the Sunday veg in the kitchen when the game started and then I went to church out of the way. I didn't see any of his performance until I came home and I knew that the 'ship was in dock' as it were and all was safe."
She later suggested "the prayers of the Welsh Congregational Church were answered".
Stay up to date with the latest news stories from a Christian perspective. Sign up to our daily newsletter and receive more stories like this straight to your inbox every morning.