Guzan has been between the posts while Villa have let in 17 goals in the last four Barclays Premier League games against Chelsea, Tottenham, Wigan and Swansea.
But Lambert is full of praise for the American's individual performances, even though Shay Given could come into contention for Saturday's FA Cup tie with Ipswich.
Given has played in Villa's Capital One Cup ties during their march to the semi-finals.
Lambert said: "I think it might have been harder for Brad if he was a young guy, but Brad is a top professional and really mentally strong.
"From that point of view, yes of course it hurts losing goals, but I don't think it will affect him, not knowing him the way I do.
"I certainly wouldn't put Brad out of the team for what has happened.
"I don't think it's Brad Guzan's fault for the 17 goals we've let in. If it was not for Brad Guzan, it might have been 34."
Given made himself available this week to play for the Republic of Ireland again after announcing his retirement in the aftermath of the European Championships.
And Lambert believes the veteran is still playing well enough to represent his country.
He said: "If that's Shay's thinking, then fine. For me, the way he's trained and the way he's played in the games has been excellent.
"He is no doubt good enough to come back and play for Ireland and has played well in the Capital One Cup matches.
"I'm just fortunate to have two such fine keepers available to choose from."
Lambert concedes that he would like to rest striker Christian Benteke once Gabriel Agbonlahor and Darren Bent return from injury.
Benteke has endured a heavy schedule and played in all four of Villa's games over Christmas and the new year.
Lambert said: "I'd like to rest Christian because he's played a lot of games. He's played a lot of games for Belgium and his season with Genk had started before he joined us in August.
"But with Gabby and even Darren out injured, it has not been great. There have been a lot of injuries up front."