Ai Miyazato fired a 5-under 67 on Saturday to grab a 4-stroke lead after three rounds of the RR Donnelley LPGA Founders Cup.
Miyazato, who will go for her 10th LPGA Tour title on Sunday, finished 54 holes at 19-under-par 197 at Wildfire Golf Club at JW Marriott Phoenix Desert Ridge Resort & Spa.
Stacy Lewis had carded a 6-under 66 to move within two of Miyazato. After the round, she was assessed a 2-stroke penalty for her caddie testing the surface of a bunker on No. 16. That dropped her four back at minus-15, which left her tied for second with the second-round leader Jee Young Lee (72).
If Lewis can rally and win, she would become the No. 1 player in the Rolex World Rankings on Monday.
Angela Stanford (65), Anna Nordqvist (67), Gerina Piller (68) and Lizette Salas (66) share fourth place at 13-under-par 203.
Defending champion and current No. 1 Yani Tseng carded her second straight even-par 72, which left her tied for 63rd at 2-under-par 214.
Miyazato birdied three of four holes from the 12th to move three clear of Lewis. At the 16th, Lewis drove into a fairway bunker. While discussing what type of shot to play with her caddie, Travis Wilson, he went into the bunker to look at the shot.
Wilson was deemed to have tested the surface of the sand by dragging his foot. Lewis was given a 2-shot penalty after the round for this. She made par there and at 17.
Lewis had birdied the 18th from 10 feet out to move within two. After the round, the penalty was assessed and pushed her four strokes behind Miyazato.
"I didn't see Travis do anything when we were playing, I wasn't looking at his feet obviously. So we looked at the video and you have to slow it down, zoom in on his foot, he walks into the bunker, he kind of pushes���and he kind of bounces his knees a little bit and his foot turns," Lewis explained.���"And that was kind of the big indicators that his foot turned and you could kind of hear the sand crunch a little bit.���So that's deemed to be testing the sand.
"It's a ruling on intent, so our whole purpose of that shot was to find out how much sand was in the bunker. That's the unfortunate part.���It looks like he's going in there to see how much sand is in there when that really wasn't what he was trying to do.���So more than anything I just feel bad for him because he feels awful, but he's the best caddie out here, so we'll be fine."
Lee led by one at the start of the round, but opened with 11 consecutive pars and never challenged.
Miyazato, who tied for second last year, chipped to tap-in range at the par-5 second and that birdie gave her a share of the lead. She also birdied the par-5 fourth to move one clear.
The 27-year-old ran off six consecutive pars from the sixth as Lewis caught fire to grab a share of the lead.
Lewis birdied the second and followed with a short birdie putt on the third. At the seventh, she converted her third birdie effort of the day to move to minus-14.
Around the turn, Lewis drained back-to-back 7-foot birdie putts at 10 and 11 to join Miyazato atop the leaderboard.
Miyazato responded with a 20-foot birdie putt on the 12th and a kick-in birdie at 13 to move two clear. She blasted from a bunker on the par-5 15th to two feet and knocked that in for birdie and a 3-stroke lead. Miyazato parred the last three to end there.
"It was a pretty solid round. I didn't hit any bad shots and I had a few birdie chances out there, but I couldn't make it," Miyazato said. "But towards the end, I started to feel more comfortable with my putting. The last putt was really clutch, I think, so that's going to be good momentum to tomorrow."
Lewis parred four in a row from the 12th. She scrambled for par at 16, but was later penalized and that changed to a double-bogey. A birdie at the last left Lewis four back with one round to go.
NOTES: Miyazato owns at least of piece of the 54-hole lead for the 12th time in her tour career ... She has won two in a row and seven of the 11 overall ... Miyazato won twice last year after tying for second at this event ... Inbee Park's 8-under 64 was the low round of the day and helped her jump from a tie for 39th into a share of eighth place.