Tseng, the 2008 LPGA Championship winner, had a 72-hole total of 9-under 283 on the par-73 Commonwealth Golf Club.

Hitting 17 greens in regulation Sunday, she birdied the final two holes to all but end any challenge from Webb and Davies in the final group behind her.

Defending champion Davies shot 71, including a birdie on 18, to finish second.

Four-time Open winner and third-round leader Webb missed three putts for birdies inside four feet on the back nine and was third after a 74 and was four behind Tseng.

Australian Katherine Hull, who shot 72, finished tied for fourth with second-round leader Giulia Sergas of Italy (74), five off Tseng.

Webb wore a white shirt with blue-and-green trim - the same as last Sunday when she shot a course-record 11-under 61 at Royal Pines to win her seventh Australian Masters title.

But while the shirt was the same, the outcome was very different as Webb, playing for the fourth week in a row after previous stops in Bangkok and Singapore, faltered in the closing stages.

Instead Tseng was rewarded for steady iron play on the back nine - capitalizing on birdies on eight and nine to come home with a bogey-free finish.

"It was very exciting, my whole body is still shaking," Tseng said before the trophy presentations. "My heart is still at over 200 beats a minute.

"I just felt I needed to get some more birdies coming home, and it worked out," added Tseng, who said she plans to return to Taiwan and will share the Australian Open trophy with family and friends.

Webb started the day with a one-shot lead over Sergas and began with two birdies.

"I got off to a really great start and was feeling really good," Webb said. "I played a couple of scrappy holes on six and seven and really lost a lot of momentum.

"I just didn't hit it as good after that for some reason.

I didn't trust myself as much as I would have liked and then the putts just weren't going in. Seven under is an incredible score around here today."

Meanwhile in Miamil South African duo Ernie Els and Charl Schwartzel head into Sunday's final round of the WGC-CA Championship at Doral tied for the lead on 12-under par, one stroke ahead of Ireland's Padraig Harrington.

The 25-year-old Schwartzel produced a five-under 67 in the breezy sunshine of the Blue Monster course on Saturday while Els, the overnight leader, had some ups and downs in his round of 70.

Els, who has not won on tour in two years, will now play the final round with a compatriot 15 years his junior and who he hosted while Schwartzel practiced last week.

Schwartzel, who won two early events on the European Tour this year, will go head-to-head with a player who his father once partnered and despite his admiration of Els, who won this competition when it was held in Ireland in 2004, Schwartzel said he was only focusing on winning the title on Sunday.

"When you are out on the course it is every man for himself. I am sure we'll have a good time and a good battle," he said.

Els continues to look confident but missed a three foot birdie putt on the 16th, having earlier missed from four feet on the 13th to bogey.

"I felt a little uncomfortable on those shorter putts today. I think it could have been the breeze," said Els.

"I'm six foot four (1.93m) and I move around a little bit, or it feels like it. I think it was a bit of a weak point today and it cost me a little bit." Harrington would also have had a share of the lead had he not three putted the 18th to end a fine round with a bogey.

The Dubliner made six birdies in his five-under 67 round that was faultless until the final hole, but he remains in strong contention for Sunday along with Australian Robert Allenby (71) who is two shots off the lead.

"It leaves a sour taste to bogey the last but finishing 11-under or 12-under has no real effect on the outcome tomorrow. There are three of us up there, whoever plays the best golf is going to win the tournament," said the Irishman.

German Martin Kaymer produced the day's top round with a six-under 66 moving him into sixth place on eight under, one shot ahead of Fijian Vijay Singh (70), Dane Soren Hansen (71), Britain's Paul Casey (68) and American Matt Kuchar (67).

Phil Mickelson, the world No. 3 and defending champion, hit five birdies and five bogeys in his even-par round and ended up in some pain after jarring his elbow playing his second stroke on the 18th.