James Hook was given the shirt for the opening World Cup clashes against South Africa and Samoa. When Leigh Halfpenny came on for Hook against Samoa, the Blues winger played a crucial role in Shane Williams' match winning try and looked to have done enough to earn a starting spot against Namibia with a shoulder injury ruling out Hook.
Halfpenny has indeed got a starting spot, but on the wing which has opened the door for Byrne at full back. And it's an opportunity the 31-year-old Clermont Auvergne bound star is determined to grab with both hands.
"It is nice to be back playing again. It's all about game-time. The more time I get on the pitch, the better I play. With Hooky being out it's a big opportunity for me, and I have got to make the most of the chance.
"I have enjoyed being part of the squad, but there is only so much training you can do. You want to be involved in the match 22, so it's great to have been picked."
Despite being one of the most experienced backs in the backline with 44 caps next to his name, Byrne will be making his World Cup debut.
"I was just so happy to have made the squad for the tournament, but now I have been given the chance I don't want to disappoint against Namibia," he added.
"Of course it's a massive opportunity for me. Maybe there is a position to grab for the next few weeks. I have been waiting for this. I want to challenge for a place in the team for the rest of the tournament. I want to put a marker down for the Fiji game."
Wales, even with 11 changes to the side which started against Samoa, will be heavy favourites for the match but Namibia are promising to leave the tournament with a bang.
They have conceded 185 points in losing to world champions South Africa and also Samoa and Fiji, with but skipper Jacques Burger said: "We are definitely going out with a positive outlook. Even if it sounds impossible, we have to go out and try to win.
"We have to play rugby like a winning side. That means less mistakes, sort out first-phase ball and keep the ball in hand. We are going to knock on, we're going to miss tackles, but we cannot just stop working hard.
"We don't want to play a slow game. We want to play with the ball, and we've not been doing that. Whenever we have the ball we don't look bad. If you play against top sides and you don't have a lot of ball then they are going to score a lot of points against you, which is what the Springboks did against us on Thursday."
Namibia head coach Johan Diergaardt added: "It is our last game in the World Cup, it's the last chance that players will have to present themselves on this stage. We need to concentrate for 80 minutes. We cannot play just for 60 minutes and allow seven tries in the last 20 minutes.
"Most of the tries in that game didn't come from constructive work of the opposition, it was more our mistakes that led to them. I am not making any excuses, but that is the difference between amateurism and professionalism. You cannot compete, really, at all the stages at all times with a professional side.
"We just don't concentrate fully for 80 minutes, and you can't play against any of these teams with a lack of concentration for not even a second. That is too much.
"South Africa and all these big nations have the chance to play at this level again and again - 12, 14, 15 Tests a year. We don't have these chances. It is not making excuses, but it's our fourth real Test in four years at this level."