(REUTERS) - Australian Jason Day became the first player to reach the WGC-Accenture Match Play Championship semi-finals with a 2&1 victory over South African Louis Oosthuizen in Marana, Arizona on Saturday.

Helped by three birdies in the first nine holes at sun-splashed Dove Mountain, Day sealed the win with a matching par at the 17th after Oosthuizen had been troubled by an ailing back during their quarter-final clash.

Rickie Fowler joined Day in the last four with a see-sawing, one-up victory over fellow American Jim Furyk, who came from three down after 12 holes to go one up after 16 before running out of steam.

Day had trailed by one after Oosthuizen made a fast start with birdies at the second and third but then upped his game to take control as his opponent had periodic back treatment from his physiotherapist out on the course.

"We both played well today... it didn't seem like Louis had a sore back because the way he played was pretty good," Day told CBS Sports after finishing birdie-birdie-par-par to reach the last four at Dove Mountain for a second successive year.

"I've loved match play ever since I was a little kid. You just have to grind at it and keep fighting until the end. I'm just glad I got it done and I'm looking forward to tomorrow."

The Australian, beaten by eventual champion Matt Kuchar of the United States (US) in last year's semi-finals, will next face either South African Ernie Els or exciting American talent Jordan Spieth in the last four.

Fowler, wielding a red-hot putter, birdied three of the first four holes to go three up on Furyk before his opponent briefly cut the deficit to one by winning the sixth and seventh holes.

Birdies at the ninth and 11th got Fowler back to three up but Furyk again rallied, levelling the match with three consecutive birdies from the par-five 13th.

PGA Tour veteran Furyk briefly went one up with a par at the short 16th, where Fowler bogeyed, but then stumbled when he bogeyed the par-four 17th after being bunkered off the tee for the match to reach the 18th all square.

After Fowler had comfortably reached the green in two, Furyk duffed his chip from just short of the putting surface on the way to another bogey as his opponent wrapped up victory with a two-putt par.

In the other matches, Frenchman Victor Dubuisson was one up on Northern Ireland's Graeme McDowell after 10 holes and Els was two up on Spieth after 12.

The semi-finals will be played on Sunday morning with the 18-hole final scheduled to take place later in the day.