Fil-Am Dorothy Delasin , who threatened at second in the third round, failed to get going and fired a 73 for joint fifth place overall. Jennifer Rosales also had a bad day, shooting a 74 to be at the rear end of the standings at 287.
"Relieved," Diaz said of her emotions after finally getting a victory after four runner-up finishes last season.
"As much as it has been talked about, all of my seconds, no victories yet – the question ‘When are you going to get a victory?’ I got a victory. The question is over."
Diaz began the day sharing second, two strokes off Inkster’s pace, but shot a four-under-par 68. Her birdie at the 18th hole gave her a four-round total of 18-under 270, one stroke off the tournament record.
The 1998 LPGA Rookie of the Year said her birdie at the last hole came despite a poor second shot.
"Oh, I hit it awful," Diaz said of the 167-yard six-iron that left her 35 feet to the pin. "I asked it to kick right, and that was the best kick of the day. I hit it really bad.
"I said to Thad (her caddie), ‘That was really bad.’ He said, ‘Well, it’s in the middle of the green, that’s all that matters.’ That was very true."
Diaz opened the day with two bogeys, but she said she was confident she could get the round back on track. She did, with three birdies in a row from the third.
"Those are the first two bogeys of my week," she said. "I don’t think you’re ever happy when you make a bogey, but I was really happy after three birdies in a row."
Diaz added birdies at the 12th and 15th but said she was lucky not to know for sure she had taken the lead. (AFP)