SAN ANTONIO -- A major upset has already occurred in the NCAA Division II Women's Basketball Championship tournament at Bill Greehey Arena.

The sixth-seeded Augustana (S.D.) Vikings ousted the No. 1 team in the nation, the Clayton State Lakers, by a score of 81-68 on Tuesday in the quarterfinals. Augustana (28-6) is making its first appearance in the NCAA quarterfinals. Clayton State (32-1), the 2011 champion, was the only undefeated women's team in all of NCAA Division I and Division II.

Augustana will now face the winner of No. 4 Colorado Mesa and 10th-ranked Dowling in the semifinals at 7:00 p.m. ET on Wednesday.

Vikings coach Dave Krauth, in his 24th season at the program's helm, had received a number of emails from other coaches, particularly from other Northern Sun Intercollegiate Conference squads. The coaches' communications expressed great confidence in their NSIC and Central Region champions.

"I honestly felt some of the emails were not cliché ," Krauth said. "Some of them said, 'You are the best team in our conference.' We did have a very good team, and every coach echoed those comments. I want to emphasize that our team just fought hard over the last month."

Augustana defeated Minnesota State 81-73 to capture the conference title and the automatic bid to the NCAA tournament. From there, the Vikings beat Concordia-St. Paul (78-66), Southwestern Oklahoma State (68-64) and Emporia State 75-74 to advance to the tournament at St. Mary's (Texas).

Senior forward Alex Feeney's free throws with .7 seconds remaining in the regional final against Emporia State propelled the Vikings to the NCAA quarterfinals. In Tuesday's game, Feeney scored 14 points, on 6 of 10 shooting from the field and 2 of 3 beyond the arc. She also dished out five assists in the winning effort.

"We knew [Clayton State] would make a run," said Feeney. "But they were not used to being down. You could see it in their faces. The last two weeks of play have prepared us for this. We are on a mission, and we hold ourselves to high expecations."

The Vikings led the Lakers 32-25 at the end of the first half. Augustana shot 43.5 percent (10-23) from the field and made 4 of 8 in 3-point range. Clayton State hit only 25 percent (9-36, 2-8 beyond the arc). Augustana went on a tear and led by as much as 24 points (67-43) with 7:34 remaining on a layup by Andrea Whitney. But the top-ranked Lakers outscored the Vikings 28-4 and closed to within seven points (71-64) at the 1:25 mark.

Lydia Nelson of the Vikings made a layup, and the Lakers' Shacamra Jackson countered. The score went back and forth between a nine-point to seven-point lead, until Feeney fed an assist to Faith Tinklenberg, who scored a layup with 33 seconds on the clock (79-68 lead). Shaunteva Ashley sank two free throws with 21 seconds remaining, for the final score of the game.

Ashley led the Vikings with 17 points and shelled out a game-best eight assists. Tinklenberg added 15 points and eight rebounds. Also in double figures were Emily Schulte (11 points) and Cami Koen (10 points).

Drameka Griggs of Clayton State was the game's high scorer with 22 points on 8 of 18 shooting. Jackson had a double-double of 17 points and 10 rebounds and Bena Hanyard had 16 points.

Augustana shot 52.8 percent from the field (28-53) to 32.5 percent (25-77) for Clayton State. Three-point shooting played a major difference in the opening game, with Augustans hitting 58.8 percent (10 of 17). The Lakers managed only 27.3 percent (6 of 22) of 3-pointers.

"[During] the last 30 or 40 minutes, we were the better team," Krauth said. "We are a very capable 3-point shooting team."

The Vikings led 45-37 in rebounding, but also committed 32 turnovers to 16 for Clayton State.