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Iowa's startling losing streak claimed another casualty — the Hawkeyes' perfect record against ranked teams.

Iowa's offense went almost completely dark for eight minutes in the second half in an 81-69 loss to No. 8 Penn State on Thursday night. The Hawkeyes (16-10, 5-7 Big Ten) have lost five straight and the opportunity to play at Carver-Hawkeye Arena in the NCAA tournament is starting to slip.

"When you've lost five in a row it's really tough," Iowa coach Lisa Bluder said. "We go on the road now with two games and we really need to win one of them."

Morgan Johnson had 17 points and 11 rebounds for Iowa in tying a school record with her 121st career start.

Maggie Lucas scored 21 points to lead Penn State (21-3, 11-1), which has won 15 of 16 games. The Lady Lions are off to their best conference start since 2003.

Iowa will host the first two rounds of the NCAA tournament, but the Hawkeyes need to start winning again to have a shot at playing on their home court during the tourney.

Iowa hasn't won since Jan. 27. The Penn State loss was Iowa's first 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.

Penn State went on a 19-4 run during that stretch to take control of the game.

"It seemed like they amped up their defense," Bluder said. "It seemed like they just pressured a little bit more. I think they pressured hard to begin the game, and we handled it. The second half, again, forced us into some of those mental mistakes."

Lucas hit a pretty step-back jumper with 12 minutes left to push Penn State's lead 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 4½ 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.

Penn State hit 52 percent of its shots in the second half thanks to the tough defense.

"When you can get layups in transition and uncontested shots, that helps your offense," Penn State coach Coquese Washington said. "Offensively in the first half we weren't quite clicking. In the second half, I thought we got some free throws, some points in the paint and some transition baskets. That got things going for us."

Penn State's Ariel Edwards scored 15 points off the bench and Alex Bentley added 14 points.

The Hawkeyes desperately needed a win, but some of their best parts failed them against Penn State.

The Hawkeyes lead the Big Ten in free-throw percentage, but made only 11 of 19 on Thursday. They also missed on the front-end of a pair of one-and-ones in the first half.

"The downfall was our free throws," Bluder said. "That could have kept the game so much closer."

Iowa's Jamie Printy, who averages 14 points a game, missed all five of her field goal attempts, finishing with two points in 29 minutes.

Reserve guard Melissa Dixon scored 16 points for Iowa, shooting 4 of 9 on 3-pointers.

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. When Penn State went on a 12-5 run midway through the half to take control, the Hawkeyes responded with a 9-2 burst to close the gap.

Iowa had an opportunity to tie it before halftime, but a blown layup turned into an open transition 3-pointer from Lucas that gave the Lady Lions a 37-34 lead at the break.