Guzan saved Robert Snodgrass' first-half penalty and pulled off a wonder effort to deny Gary Hooper late on.
"He made a brilliant save on the penalty," Lambert said.
"He played a major part in the result but that is what we pay him for. That is his job. His job is to make saves but he has been like that for me for the past year.
"This is a big season for him with the World Cup and for us but he is an absolute top pro and top man. I have seen him do it in training every day and his performances every day have been to that standard."