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Sixteen-year-old Lexi Thompson shot a five- shot lead after the third round of the Navistar LPGA Classic.

Thompson finished 54 holes at 15-under 201 at the Senator Course at RTJ Capitol Hill Golf Club.

If Thompson can hang on Sunday, she'll become the youngest winner in LPGA Tour history.

Marlene Hagge captured the 1952 Sarasota Open at 18 years, 14 days, but that was only an 18-hole event. Paula Creamer won the 2005 Sybase Classic at the age of 18 years, 9 months, 17 days -- the LPGA Tour record for a full tournament.

Thompson would shatter both of those marks if she can win. She will be 16 years, seven months and eight days on Sunday. but she's been in this position before and failed.

Thompson shared the third-round lead with Song-Hee Kim at this year's Avnet LPGA Classic, but the 16-year-old struggled to a six-over 78 and tied for 19th.

"It definitely helps having that experience," Thompson said. "Definitely going to try to play a lot better. But I learned a lot from there. I probably got a little fast and jumbled up my thoughts. I'm just going to free swing tomorrow and just take one shot at a time and take it slow."

This week might be different for the teenager.

Thompson has been brilliant with only four missed greens through three rounds and she made only one bogey on Saturday. That came at 18 and cut her margin to five strokes. That's a pretty substantial cushion with one round to go before her name is forever etched in the LPGA Tour record book.

Meena Lee is the closest competitor after a three-under 69 on Saturday. She is 10-under par through three rounds and will be closest to ending Thompson's quest on Sunday.

Becky Morgan (72), Karen Stupples (68) and Tiffany Joh (65) share third at minus-eight.

Reigning Kraft Nabisco Champion Stacy Lewis (73), Pat Hurst (68), Giulia Sergas (71) and Jennifer Johnson (71) are tied for sixth at seven-under-par 209.

Thompson played decent golf to start with three straight pars, but broke into red figures with a 10-foot birdie putt at the fourth. After a par at the par- five fifth, Thompson closed out her front nine in brilliant form.

She hit a nine-iron to 12 feet to set up birdie at the sixth, then rolled in a birdie effort at the par-three seventh. At the par-five eighth, Thompson sank an eight-footer for birdie and she polished off her fourth consecutive birdie from 20 feet at the ninth.

Thompson made the turn in five-under 31 and with a five-shot lead.

The teenager cooled a bit on the second nine thanks to five pars in a row, but rarely was she in danger of dropping a shot. Thompson ran home a 20-foot birdie putt at the 15th and was six shots in front of Lee.

At the last, Thompson drove right up to the lip of a bunker. She couldn't save par, but it only cost her some of her huge cushion.

Next up is perhaps the biggest Sunday of her young life.

"It's definitely going to change my life and my career," acknowledged Thompson. "But, you know, just got to take one shot at a time. Can't get ahead of yourself in this game. Just got to be on your feet and hope for the best."

Juli Inkster, 51, had an ace on Saturday en route to a three-under 69. She is alone in 10th at six-under 210.

NOTES: With the Solheim Cup next week, Lewis and Inkster are the only players in the top 10 on either team...Angela Stanford, Paula Creamer, Brittany Lincicome and Brittany Lang, all fellow members of the American side with Lewis and Inkster, are part of a group tied for 11th...Defending champion Katherine Hull had a two-over 74 and is tied for 32nd at two-under par...World No. 1 Yani Tseng hasn't been sharp all week and after three rounds, she's tied for 43rd at even-par.