(Correct Day's name in first para)
MARANA, Arizona Feb 23 (Reuters) - Jason Day found it nerve-racking at the end but he could not keep the smile off his face after beating the Masters champion and a former U.S. Open winner on Saturday at the WGC-Accenture Match Play Championship.
The 25-year-old Australian stunned Bubba Watson 4&3 in the morning with an impressive five-birdie display before battling past 2010 U.S. Open champion Graeme McDowell 1-up in the afternoon at Dove Mountain.
Having previously beaten U.S. Ryder Cup player Zach Johnson and PGA Tour rookie Russell Henley this week, Day was able to celebrate his first appearance in the semi-finals of the elite World Golf Championships (WGC) event.
"It says my game is moving in the right direction, that I beat the reigning Masters champion and a former U.S. Open champion," Day told reporters after earning a spot against American Matt Kuchar in the last four at Dove Mountain.
"I've been playing great, and I'm just really, really excited to get into the matches tomorrow. I know Matt's very slow and steady, hits a lot of fairways and greens and can roll the rock when he can, and I'm looking forward to that."
Day, whose only PGA Tour victory came at the 2010 Byron Nelson Championship, has slipped from a career-high seventh in the world to 43rd and he is eager to break back into the upper reaches by producing the form he has shown so far this week.
"I have goals, and one of them is to get back into the top 10," he said. "I really think that I belong there.
"It's just a matter of how hard I want it and how hard I need to work to get it, that's all it comes down to, the commitment and dedication that I put into my game will hopefully get me there.
"But obviously this is a good start. I've had two (PGA Tour) top 10s prior to this (in 2013), and those are great for world ranking points. And I'm in the final four tomorrow, and that's regardless of where I finish."
For the Australian, Saturday produced two very different matches as he outplayed Masters champion Watson but then found the going tough against gritty Northern Irishman McDowell.
"The funny thing about match play is that it's so up-and-down," Day said. "If you get up to a good lead like I did on Bubba, it's very, very tough to get those holes back.
"I started off great against Bubba, and luckily enough I finished it off pretty quick. G-Mac, on the other side, we were going back and forth. It was very, very stressful. I'm glad I got it done."
McDowell went 2-up on Day in their quarter-final after just three holes but then surrendered that advantage with bogeys at the fifth and seventh.
Day went 1-up with a birdie at the par-five 11th but the Northern Irishman got back to all square by sinking an eight-foot birdie putt at the 14th.
McDowell again faltered with a bogey at the par-four 17th, missing the green to the left with his approach to go one down, and Day held on to seal the win as both players parred the 18th.
"I feel like my mind is going every which way right now," Day smiled.
"Just to play the way I did on the back nine was very, very special. The whole game today felt really, really nice, and I'm looking forward to tomorrow." (Editing by Greg Stutchbury)