The number 13 seed came through 6-3 6-2 7-5 after one hour and 33 minutes of tennis.
Both players gave little away early on, but it was Haas who made the first breakthrough of the first set when Wang failed to hold serve in the fourth game. The German won his next three service games to love as he closed out the set.
Wang struggled to cope with Haas as he lost his first two service games of the second set, allowing his opponent to open up a 4-0 lead. Haas did not let his advantage slip as he went on to claim the second set in just 25 minutes.
The third set was a much closer affair with both players holding serve well, but Haas made a crucial break at 5-5 before serving out the match.