The hard-working midfielder will find himself in opposition to current club colleague Ben Davies and former Spurs man Gareth Bale when the two nations meet in Lille with a place in the semi-finals at stake (kick-off 8pm).
Mousa obviously knows Ben and Gareth well and intends to catch up with both of them – but only after the game.
That's because the 28-year-old's sole focus at the moment is on making it through to the next round.
“It’s always nice to play against current team-mates or old team-mates – it makes the game extra-special," said Mousa.
"We all know they (Ben and Gareth) are very good players and we have a lot of respect for them, but I think on our behalf and from them as well it doesn’t make a difference – we just want to win the game.
"After the match we’re going to shake each other’s hands but during the game it’s going to be a battle."
Mousa's fellow Belgian international Toby Alderweireld says the Red Devils are keen to avoid a repeat of the 1-0 defeat they suffered against Wales in qualifying for the competition.
"We’ve had difficulties playing against them in the past because they defend very well – we know that sometimes they have five at the back and they are difficult to break down," he said.
"It’s different to the qualifying games against them as it’s a quarter-final at the Euros but, of course, we can learn from those matches. We know that we will have a very tough opponent and it won’t be easy."
From the Welsh side, Ben has helped his nation win three of their four games at the tournament so far and he’s keen to carry that momentum into tonight's match.
"We are all really looking forward to it and, to a man, we will give 100 per cent to try to progress to the semi-finals," he said. "The character we’ve shown at the tournament so far has been great and we’ve had some top performances so hopefully we can take that forward and get past Belgium.”
On Sunday night, another of our players will be in quarter-final action as Hugo Lloris and France meet Iceland, kick-off 8pm.