The American made several impressive saves as the hosts looked to climb into the top half of the table but had no chance of stopping Dwight Gayle's solo effort at the death - a goal that lifted the Eagles out of the relegation zone.
For Paul Lambert's side, it was a fourth straight defeat - but Guzan remains hopeful the Villans can turn their festive period around when they host Swansea on Saturday.
He said: "That's football. It's not the way we wanted to finish the game and not the result we wanted going into it.
"It's a bit of a blow but the good thing about the Christmas period is that we can turn it around on Saturday.
"We have to put this behind us and find a way to come out and get a result on Saturday."