Huddersfield Town secured their first Premier League win since December when they defeated Bournemouth 4-1 at John Smith's Stadium on Sunday.
The Terriers took the lead through Alex Pritchard, who scored his first goal for the club since arriving from Norwich last month. Their advantage only lasted six minutes before Junior Stanlisas got the visitors back on level terms.
Steve Cook then scored an own goal from Mounie's deflected shot with just under 25 minutes to play. Robin van La Parre scored from the spot in stoppage-time to seal an incredibly valuable win for Town.
The Yorkshire club are now out of the relegation zone, sitting one point above 18th placed Southampton.
"It was a huge win for all of us," Wagner said. "We said before the game that this is massive for us and that after Old Trafford we had the difficult fixtures behind us.
"Now it's time to build up momentum against opponents which are in front of us, against whom we are more competitive.
"But it's one thing to speak about it and another thing - and this shows character - to do it and the players have done that."