Sixteen-year-old Lexi Thompson became the year history of the LPGA Tour Sunday when she captured the Navistar LPGA Classic.

At 16 years, seven months and eight days old on Sunday, Thompson obliterated the former mark.

"I definitely knew I could hold a record," Thompson said in a televised interview. "I was just focusing on playing the golf course today and doing my best. That's all I could do."

She shot a final-round, two-under 70 and cruised to a five-shot victory. Thompson finished at 17-under 271 and instead of the traditional champagne and beer bath for first-time winners, Thompson was doused with water on the 18th green.

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, nine months, 17 days -- the former LPGA Tour record for a full tournament.

Tiffany Joh posted a four-under 68 and took second at minus-12. Angela Stanford fired a six-under 66 on Sunday and came in third at 11-under 277.

But Sunday belonged to Thompson.

Armed with a five-shot lead at the start of the final round, Thompson's lead grew to as many as seven on Sunday. She tripped to back-to-back bogeys at 11 and 12 and her cushion shrunk to three when Joh went on a birdie run, but Thompson birdied 16 and 17 to make it a special walk up 18.

"I was a little nervous on the first tee, I'm not going to lie," she said on TV. "I knew I was playing pretty good lately. Came through here."

Thompson wasted little time in getting into red figures on Sunday. She poured in an eight-foot birdie putt at the second, then collected her second birdie at the par-five eighth. Thompson was seven in front of the field, but trouble loomed after the turn.

At the par-four 11th, Thompson knocked her approach in a greenside bunker. She blasted out to eight feet and her par putt came up short. She missed a five- foot par save at the next hole and the lead was down to five.

Thoughts of some past hiccups could've popped up for Thompson.

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

To make the situation harder on Thompson, Joh birdied four in a row, including a chip-in at 15 to trim the gap to three.

"I was maintaining it. I was just focusing on my own game and keeping steady," Thompson said of Joh's run at first.

Thompson answered more like a seasoned veteran, than a girl recently eligible for her driver's license.

When Joh knocked her tee ball to eight feet at the 16th, Thompson nearly holed her's. Joh missed the birdie putt, but Thompson tapped in from two feet to get the margin back to four.

At the par-five 17th, Thompson laid up with her second, then wedged her third to 15 feet. She rolled in that birdie putt, then it was all about fighting the smile, knowing a historic victory was eminent.

"Coming up the 18th, all of the pressure was just let off," Thompson said on television. "I just waved to the fans and everybody."

She made par at the last and after a correctly signed scorecard, she was the youngest winner in tour history.

Thompson was the youngest player to play in, and make the cut in an LPGA Tour major, however, she is now a winner.

But, Thompson is not yet an LPGA Tour member.

Due to the tour's age requirement policy, Thompson isn't allowed to be a member. She can petition the tour for membership and Commissioner Mike Whan can decide her fate.

"I don't really know right now," Thompson said when asked of her future. "This is all a big thing going on right now, so going to see where it goes in the next few days."

Brittany Lang (67) and Karen Stupples (70) tied for fourth at 10-under 278. Lang will be on the American Solheim Cup team, Stupples on the European side, but both are headed to Ireland Sunday night for next week's competition at Killeen Castle.

Stacy Lewis (70) and Meena Lee (73) shared sixth at minus-nine.

NOTES: Thompson pocketed $195,000 for the victory...World No. 1 Yani Tseng shot a three-under 69 and tied for 25th at three-under par...Katherine Hull, the 2010 champion managed an even-par 72 and shared 34th at minus-two...Next week is the Solheim Cup and the U.S. has won the last three stagings.