Tom Ince's stoppage-time goal was the solitary strike that kept all three points in Yorkshire and sent Huddersfield up to 14th, seven points clear of the relegation zone.
Wagner hails "massive win" for Terriers
Following the victory, the Huddersfield manager opened his press conference by stating: “I’m delighted for the players and the fans. They were incredible today and they deserved that late goal."
While acknowledging that his side knows the job isn’t done yet, he also admitted: "that is a massive win for us”.
He also stressed that “everyone knew how important this game was before kick-off, but we tried to focus on ourselves".
Wagner said: “We wanted an aggressive, uncomfortable game against a decent Watford side" and added that "the players did it excellently”.
Huddersfield boss admits game was "very emotional for us"
Regarding Ince's stoppage-time winner, Wagner said: “That was a fantastic finish to the game for us; very emotional.
"The game was very even, with not a lot of clear-cut chances. I was very pleased with how the players defended before the magic moment came."
He lauded his players' ability to handle the moment.
Wagner added: “I wasn’t surprised that the players coped with the circumstances today. We have played so many games that people have described as ‘pressure games’ and we’ve shown we can focus on the task at hand.”
"Very pleased" for Ince, says Wagner
The win is crucial for the Terriers' chances to stay in the top flight and the manager was delighted for Ince.
He commented: “I’m very pleased for Tom Ince. He has never given up for us, which is what it’s all about. I’m happy that he gets the headlines today”.
While the Terriers boss knows his side made "a big step today," he admitted that he is "totally sure" that his side will need further points.
However, he also feels that: "The players are performing well and have good momentum because of it”.