The England winger was reluctant to accept that the Welshman's effort had eclipsed his.
Johnson said with a smile: "David's was a great strike, wasn't it? But mine was probably more important, wasn't it?
"The game is never finished at 1-0, especially here. They put a lot of pressure on you, but it was nice to get that cushion and with 15 minutes left, there was only going to be one winner from there.
"It was fantastic and I think well deserved. It was comfortable in the end, and we maybe could have had a couple more goals."