The 53rd-ranked Haase, playing in his first final, is the first Dutch winner of an ATP event since Martin Verkerk won in Amersfoort, Netherlands, in 2004.
Haase is the eighth player this season to become a first-time champion on the ATP tour.
“This is a super feeeling,” said the 24-year-old Dutchman, who won eight titles on the lower-ranked Challenger circuit. “I was hoping for a chance this season to win my first big title and I am really happy that it happened here.”
Haase missed most of the 2009 season after right-knee surgery and is now certain to enter the top 50 for the first time. He had four aces and broke Montanes’ serve five times.
The 30-year-old Montanes, who defeated top-seeded Juan Ignacio Chela in the semifinals, is now 5-5 in career finals — all of which were played on clay.
Haase saved five break points in a 10-minute opening game full of long baseline rallies. The set went with serve until Haase converted his third set point at 5-4 when Montanes sent a forehand wide.
Five consecutive breaks early in the second put Montanes 4-3 up before the Spaniard clinched it with a love game.
Haase won eight of the first nine points in the decider and added another break to go 5-0 ahead. He used a cross-court forehand on his second match point to close out the victory.
In Washington, Gael Monfils put one hand on the trophy of the Legg Mason Classic by beating Janko Tipsarevic in straight sets Friday while his four main rivals all lost.
The top-seeded Frenchman won 6-4, 6-4 to set up a semifinal against big-serving American John Isner, who blew away Viktor Trocki in the final set, winning 7-6 (5), 3-6, 6-1.
Monfils and No.11 Isner are the only seeded players left in the draw after Friday’s elimination of Serb pair Troicki and Tipsarevic, third and sixth respectively, plus No. 5 Fernando Verdasco and No.7 Marcos Baghdatis.
Czech veteran Radek Stepanek beat Spain’s Verdasco 6-4, 6-4, and will next take on American Donald Young, who downed Cyprus’ Baghdatis 6-3, 7-6 (4).
For Monfils and Isner, it will be a rematch of their 2007 semifinal in Washington, which the American won in a third-set tiebreaker.
Zvonareva to face Ivanovic in semifinals
In San Diego, California, Vera Zvonareva has fended off Sabine Lisicki, earning a 6-3, 3-6, 6-4 win on her fifth match point to lead the top three seeds into the semifinals of the WTA San Diego Open.
The top-seeded Russian will play resurgent Ana Ivanovic, who escaped from 1-4 down in the opening set to defeat China’s fourth seed Peng Shuai 6-4, 6-2.
Ivanovic, the 2008 Roland Garros champion, has been re-booting her game with a new coach and trainer and is seeing her hard work pay off.
The Serb, a former world No. 1 who is trying to improve on her 18th ranking, equalled her best showing of the season by reaching the final four.
Ivanovic spun in an ace for a match point and advanced as Peng, who had her left hip taped in the second set, returned wide after 77 minutes.
“It was my first night match,” said Ivanovic. “I’m happy I managed to calm down and get the break back.
“Then I was back in the match, I’m very pleased.
“Zvonareva will be a tough opponent, she’s just coming off a title. But it will be a good test for me to see where my game is and what I need to work on.”
Zvonareva, twice a Grand Slam finalist in 2010, overcame six double-faults to triumph in two and a quarter hours.
The Russian, who won her 12th career trophy in Azerbaijan last month, claimed her eighth consecutive win to drive her record in 2011 to 28-6 on hardcourts.
Second-seeded Andrea Petkovic earned a win for Germany as she motored past US teenager Sloane Stephens 6-2, 6-1 in 66 minutes.
Petkovic next faces third-seeded Agnieszka Radwanska, who shrugged off a sore right shoulder to beat eighth-seeded Daniela Hantuchova of Slovakia 0-6, 6-4, 6-4.
