Michelle Wie speaks to reporters after learning she had been disqualified from the LPGA State Farm Golf Classic on Saturday in Springfield, Ill.

SPRINGFIELD, Ill. ? After finishing Friday and Saturday in second place at the State Farm Classic, Michelle Wie was one good round away from finally living up to her deep potential.

Then, minutes after tapping in her last putt of the third round, Wie sat red-eyed at a folding table in front of a few dozen baffled reporters and photographers, explaining why she’d been disqualified from the tournament.

The 18-year-old, playing her best golf of the year, broke one of the game’s most basic rules: She failed to sign her scorecard before leaving the scoring area.

“I don’t know why or how it happened,” Wie said.

Wie took no questions before leaving the clubhouse at Panther Creek Country Club. She climbed into an SUV with her parents and drove away.

That left Yani Tseng leading the tournament at 18 under, followed by Katie Futcher at 16 under and Hee-Won Han and Ji Young Oh another shot back.

Sue Witters, the LPGA’s director of tournament competitions, disqualified Wie in a small office in an LPGA trailer at the course after asking her what had happened.

“I felt like I was telling somebody that there was no Santa Claus,” Witters said.

And with that, Wie was gone from a tournament where either the $255,000 winner’s purse or the $155,252 second prize would have put her comfortably within the top 80 money winners for the year – and virtually guaranteed her a place on the LPGA Tour next year.

Wie shot a solid 67 on Thursday, then a 65 on Friday that tied her with Tseng.

Wie told reporters that after she finished her round Friday, she left the tent just above the ninth green where players sign their scorecards. She was chased down by volunteers working in the tent, who pointed out she hadn’t signed.

Wie returned to the tent and signed the card, and “I thought it would be OK,” she said.

But Wie, according to Witters, had already walked outside the roped-off area around the tent. At that point, the mistake was final, Witters said.

Witters said she and other tour officials didn’t learn about the mistake from volunteers until well after Wie teed off Saturday morning, so they let her finish the round.