"I was greedy. I got too aggressive and paid for it," said Rosales, referring to the lone black mark on her scorecard teeming with birdies a double-bogey 6 on No. 9. "Its tough to take, but you have to move on."
The 25-year-old Rosales had the most frustrating day among the leaders, seeming to relive in one round her up-then-down performance at the US Open, where she led after 54 holes only to finish fourth.
After going to 6-under through 17 at the Legends, Rosales double-bogeyed the par-4 9th, her final hole, requiring two shots to get out of a fairway bunker.
"It was a mental thing on the 9th hole. I missed my drive on the right and it went into the bunker. I had a shot into the hole. It hit the lip of the bunker and came back and I had to hit it out, advance it to about 100 yards and made double from there," said Rosales, who rattled off five birdies on her last nine holes.
She slid to joint fifth with Angela Stanford and Dawn Coe-Jones, three strokes behind Mallon, who rallied from four strokes down with a flawless 65 to win LPGAs most coveted crown.
Mallon matched that 65, another seven-birdie, bogey-free round to take a two-stroke lead over Gloria Park, Johanna Head and Kris Tschetter, who all shot 67s.
Mallon has extended her streak to 43 straight holes without a bogey the third-longest stretch on the LPGA Tour. And she is 17 under for her last three rounds of competition.
"You have to carry your momentum and know how to handle that," Mallon said. "And when youre playing well you have to go with it and dont fight it. And certainly thats what Id like to do this week."
Mallon, who only played in Wednesdays Pro-Am, credited the time she took to rest this week.
"I felt like my legs were back with me again," she said.
Besides Mallon, whos second on the money list, its a wide-open field reflective of an event thats missing Annika Sorenstam and Grace Park, who have combined to win five of this years 15 tournaments.