The winger has been forced to sit out the last three games after being sent off at the end of the 2-1 home defeat to Manchester City last month , following a bust-up with Leroy Sane.
Van La Parra has since apologised for his actions , which were even more frustrating as it curtailed a rich vein of form for the Dutchman, highlighted by a sumptuous strike against West Bromwich Albion.
And, speaking to the media ahead of the visit of Premier League champions, Wagner confirmed he had no new injury doubts and that the forward would be back pushing for a starting berth.
“He will be back in the squad - before his suspension he made some big steps offensively and defensively,” said David Wagner . “He has something to prove.”
On Mounié, Wagner said: “He is a player who needs his best fitness level to perform.
“He is one of the fittest, strongest guys in our squad and he needed time to get back to that level.
“I was very pleased for him (against Brighton) and us because we need goal scorers and goal threats in the squad and he is one.
Although describing Chelsea as "one of the biggest teams in England", Town’s boss was keen to downplay their status and purely focus on his own side in order to pull off an unlikely victory.
He added: “It’s important we focus on ourselves. We know exactly what we have to do to have a small chance and our supporters know what they have to do to help us have this small chance.
“We cannot expect a positive result tomorrow but what we can expect is it to make it as uncomfortable as possible for them.
“We will then see what we can get out of the game.”