Last week Gatland declared Charteris was currently the best lock in the Wales team and thoroughly deserved his starting spot against South Africa. Charteris repaid the faith shown in him by producing his best display in a Welsh shirt.
Now Davies is in unknown territory - on the outside looking in but he is determined to haul himself back up to the forefront of Gatland's mind when it comes to team selection.
"Obviously, I was bit gutted not to be starting against South Africa, but it is one of those things," admitted Davies. "Rugby is like that - it's swings and roundabouts.
"One day you are the first choice and you are playing well, but the next day you are out. But I still believe in my ability and I know I can offer a lot of things other locks can't.
"But, look, Luke and Alun were outstanding at the weekend, and I respect them for that. Whoever gets the lucky seat, as they say, whoever starts knows they have got another second-row pushing.
"For me now, it's about training well and putting pressure on Luke and Alun. We are a good group of guys, us three. We talk a lot about the game and we bounce off each other.
"We are all supportive of whoever gets the start. I am probably not quite in favour at the moment, but I have got to keep working hard and push my way back in."
Wales slipped up 17-16 last Sunday against South Africa in their opening Pool D clash of the World Cup. Everyone in the Welsh camp is fully aware they can't afford a similar fate against Samoa this weekend.
"Winning is the next step for us, finishing these games off. We have said it in the past about pushing teams very close but not quite having the win at the end.
"Maybe it's a bit of luck, but once it comes - that big win - I think a lot will follow. Now, it is quite easy, it is knockout rugby. If we don't win every game, we are out.
"Before the tournament, it was 'you can win this game, you can't win that one.' Now we have to win them all.
"That is the pressure we put on ourselves, to try and perform at the highest level. We are sick and tired of being told we can't do things.