The 25th-ranked Dolgopolov's previous three finals appearances, including one victory, came in 250-level events.
Dolgopolov relied in his high-risk, high-reward approach.
"It's a part of me, my personality," said Dolgopolov, who added that he enjoys racing cars. "I like risking in life, so I do that on the court. I'm just a risky person. I don't think about the percentage. I like to do it my way."
Dolgopolov agreed with his opponents who said his unorthodox shots keyed his success.
"They are a bit unique. They are a bit crazy," Dolgopolov said of the shots. "Sometimes, it works. Sometimes, it doesn't. But that's my way to play, and I'll be playing pretty much the same way."
There were two rain delays in the first set, totaling 2 hours, 52 minutes.
Haas won the first-set tiebreaker to hand Dolgopolov his first set loss of the tournament.
Both players held serve in the second set until Dolgopolov, from the Ukraine, broke Haas in the final game for the German's first set loss in the tournament. Dolgopolov broke Haas' serve twice in the final set.
"Obviously, I'm a little bit frustrated right now, still," Haas said. "I thought I had some chances to maybe win this title, and I really wanted it. Always tough to lose, even when you've had a great week."
Dolgopolov hit 36 winners to Haas' 25.
"He's a shot-maker, and he goes for his stuff," Haas said. "When he's on, he's tough. Boy, he's tough."