The 21-year-old has not lost a set so far at this year's grandslam, but knows he will be up against a stern test in the shape of Haas, who was once world number two.
Murray says he can't spot many weaknesses in Haas as a player, but is concentrating on continuing his promising run of form at SW19 so far.
The Scottish talent commented: "The more matches I play, the more confidence you get in all your shots, it's just been really relaxed so far and it's a great advantage to me.
"Neither of my matches have been completely perfect but I'm fresh and I've not used up too much nervous energy."
Haas has enjoyed mixed fortunes at the All England Club over the years. He reached the fourth round for the first time last year but was forced to withdraw with an abdominal injury and was unable to face eventual champion Roger Federer.
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