Upson said: "I was hoping to cement a place in the squad and to confirm I'm up to the challenge of playing for England. I feel I'm on the way to achieving that.
"Establishing myself is something that is very important to me. It is something I have been working hard to achieve and I want to keep going and I want to show people I deserve to be here and am capable of playing.
"It is important for me not to be regarded as fill-in for John Terry and Rio Ferdinand. It is something I want. That is my goal. I just want to keep improving and keep getting the opportunities to play and prove myself to people."
Upson knows he will have to stay on top of his form to do so.
"It is a massive challenge - and it probably wouldn't be as much fun if it wasn't such a big challenge - but I've got to just keep heading in the right direction and working hard and see what happens," he believes.
"I am approaching it in a different mentality now. You have to approach it in a way where you feel you deserve to be there - otherwise you won't play very well.
"As a younger player, when I was involved with England squads, I wasn't as positive. I wasn't as mentally strong as I am now and probably didn't go into games in the right frame of mind.
"That showed in my performances. I am a few years older now, have made a few more mistakes, and understand things a bit more - and I feel comfortable and really happy to be here as part of things."
He accepts it is not just the established stars but emerging players too who will be targeting a place in the squad for South Africa.
"Being part of things for the World Cup in South Africa is a big goal of mine," he confirms.
"It is something I am focusing on - but who knows?
"There is a lot of good young talent coming through - and, if there are injuries or suspensions, we still have that depth to field a very strong team."