Two goals from Heung-Min Son condemned the Terriers to a 2-0 defeat that nudged Yorkshire’s sole top-flight representative down a place in the league table to 15th.
Three points still separate Huddersfield from third-bottom Crystal Palace, who host Manchester United tonight at Selhurst Park.
Defeat dashed any hopes of Town clinching a third straight top-flight win for the first time since 1956 but Wagner insisted his side had not lost any momentum in the battle to avoid the drop.
“We were beaten by quality,” said Wagner. “We had fighting spirit, attitude and some good moments, particularly in the second half. But we have to be honest and say it was a deserved defeat against a quality side.
“Nothing that will disturb our momentum. We knew it would be tough at Wembley. But everyone left with their heads held up.
“The second goal said everything about the game. We had a chance that we couldn’t score and seconds later we made a missed pass, Harry Kane played an unbelievable pass and they scored.”
Explaining a switch of tactics early in proceedings, Wagner added: “We thought it would make sense to try and start on the front foot, and press them high. But it didn’t work out so we went deeper for the rest of the game.
“This was better. We gave them less opportunities. Defeat is not what we like but we can leave this behind us very quickly because of the quality of the opposition.
“We said immediately after the game in the dressing room, ‘Don’t get too disappointed – let’s start to build up the excitement for next Saturday when we meet Swansea in our fortress’.
“We are in a wonderful situation where we have two home games against teams in and around us. We have the momentum that has not been disturbed by this result.”
Alex Pritchard limped out of the game with the club where his career began but Wagner expects the January signing from Norwich City to have recovered from a dead leg to face Swansea.
Match report: Page 3