Maggie Lucas scored 21 points and No. 8 Penn State clamped down on Iowa in the second half to earn an 81-69 win Thursday night.
Ariel Edwards scored 15 points off the bench and Alex Bentley added 14 points for the Lady Lions (21-3, 11-1 Big Ten), who have won 15 of their past 16 games.
Morgan Johnson had 17 points and 11 rebounds for Iowa (16-10, 5-7) in tying a school record with her 121st career start.
The Hawkeyes have lost five in a row, but this was their first loss to a ranked opponent in seven games. The six wins against ranked teams are the most in the nation.
The Hawkeyes hit only one field goal during a nearly eight-minute stretch in the second half as their 38-37 lead turned into a 12-pont deficit after Lucas hit a 3-pointer.
Lucas hit a pretty step-back jumper with 12 minutes left to push Penn State's lead up to double digits for the first time.
Iowa finally shook its shooting slump, but Lucas and the Lady Lions always had an answer.
After the Hawkeyes hit a pair of free throws for their first points in 4 1/2 minutes, Lucas knocked down a 3-pointer on the other end.
Theairra Taylor's layup gave Iowa only its second field goal in nearly eight minutes, but Lucas responded with a tough drive of her own, earning and converting two free throws.
The Hawkeyes led the Big Ten in free-throw percentage, but made only 11 of 19 against Penn State.
Iowa also missed on the front-end of a pair of one-and-ones in the first half.
Iowa's Jamie Printy, who averages 14 points a game, missed all five of her field goal attempts, finishing with two points.
Both teams looked tight in a sloppy first half that produced 22 turnovers and 20 fouls.
Neither team could pull away early -- there were seven ties and eight lead changes in the first half.
• Louisville 72, St. John's 58: Russ Smith scored 21 second-half points, including 12 in a row over a 3:03 stretch that put No. 12 Louisville (20-5, 8-4) ahead for good as the Cardinals beat visiting St. John's (15-10, 7-6).
Men's Top 25
• Ohio State 69, Northwestern 59: Deshaun Thomas scored 22 points and host No. 13 Ohio State (18-6, 8-4 Big Ten) used a late 12-0 run to beat Northwestern (13-12, 4-8).
• Minnesota 58, Wisconsin 53: Andre Hollins hit the go-ahead 3-pointer midway through overtime to finish with 21 points and lead host Minnesota (18-7, 6-6 Big Ten), past No. 20 Wisconsin (17-8, 8-4).
• Iowa 74, Penn State 72: Devyn Marble scored 22 points and Melsahn Basabe blocked a potential game-tying layup with 21 seconds left to help visiting Iowa (16-9, 5-7 Big Ten) hold off Penn State (8-16, 0-12).
Women's Top 25
• Duke 77, Virginia Tech 33: Elizabeth Williams and Haley Peters each matched their career high with 25 points apiece as visiting No. 5 Duke (23-1, 13-0 ACC) took a big early lead against overmatched Virginia Tech (8-16, 2-11) and cruised to the victory.
• Maryland 75, Clemson 45: Tianna Hawkins posted her 12th double-double of the season with 30 points and 12 rebounds as No. 7 Maryland (20-5, 11-2 ACC) beat Clemson (6-18, 2-11).
• North Carolina 76, Wake Forest 56: Xylina McDaniel scored 15 points to lead No. 14 North Carolina (23-3, 11-2 ACC) past visiting Wake Forest (11-14, 4-9).
• North Carolina State 76, Florida State 69: Kody Burke scored 26 points, tying a career high, to lead visiting North Carolina State (13-12, 5-8 ACC) past No. 19 Florida State (19-5, 9-4).
• Kentucky 78, South Carolina 74: Kastine Evans hit two free throws with 8.8 seconds left, and host No. 9 Kentucky (22-3, 10-2 SEC) fought back from a 14-point halftime deficit to beat No. 16 South Carolina (20-5, 8-4).
• Purdue 68, Wisconsin 58: KK Houser scored 20 points and Drey Mingo added 12 points and eight rebounds, as visiting No. 18 Purdue s (19-5, 8-3 Big Ten) rallied in the closing minutes for the victory against Wisconsin (11-14, 3-9).
• Delaware 86, Old Dominion 62: Elena Delle Donne scored 17 of her 26 points in the first half and posted seven boards and six assists to spark No. 20 Delaware (21-3, 12-0 Colonial Athletic) past visiting Old Dominion (16-9, 7-6) for its 16th consecutive win.
• Iowa State 72, Oklahoma 66: Hallie Christofferson scored 27 points and grabbed 10 rebounds as visiting No. 24 Iowa State (18-5, 9-4) beat No. 22 Oklahoma (18-6, 8-4) to move into second place in the Big 12.
• Texas A&M 78, Florida 71: Kelsey Bone had 31 points and 10 rebounds to help No. 11 Texas A&M (20-5, 10-1) beat visiting Florida (15-10, 4-7) and pull into a tie with Tennessee for the SEC lead.