USC’s Kiki Iriafen positioned herself right under the basket with under two minutes remaining. She caught an entry pass and hoisted a layup that fell through the rim with contact from Maryland women’s basketball guard Kaylene Smikle.

The forward completed a three-point play. After a final frame filled with scoring runs and lead changes, Iriafen’s latest points created a three-point deficit insurmountable for the Terps.

No. 8 Maryland lost for the first time this season to No. 4 USC, 79-74, Wednesday night at the Xfinity Center to end its best start to a campaign since 2011-12 when they won their first 16 games.

The Terps (14-1, 4-1 Big Ten) led by six at the beginning of the final period, but made just one of their final six shots — which came with two seconds left in a game that was already decided.

“They started doing a good job of punching it into Kiki,” senior guard Shyanne Sellers said. “We kind of got sealed too deep and got buried.”

USC (15-1, 5-0 Big Ten) sophomore JuJu Watkins, who averages 25 points, was primarily defended by fellow guards Bri McDaniel and Sellers. The Maryland junior made it difficult for Watkins to generate any offense to start.

The Trojans’ guard only accounted for four points in the first quarter. She committed three turnovers while missing all three of her 3-point attempts.

Watkins finished with 21 points and nine rebounds but shot inefficiently. She also notched eight turnovers and fouled out in the final minute.

[No. 8 Maryland women’s basketball remains undefeated with 74-66 road win over No. 23 Iowa]

“I wanted to make everything difficult for her,” Sellers said. “We just wanted to make her night tough, and we did that.”

Sellers and Saylor Poffenbarger led the Terps’ offense amid Watkins’ slow start. Poffenbarger scored the first five Maryland points while Sellers added five in the first 10 minutes, including a coast-to-coast basket which she finished with an underhand layup.

Forward Christina Dalce scored a pair of baskets in the paint as the Terps led 20-18 after one quarter.

Sellers ended with a game-high 26 points, with 17 coming in the second half. Dalce scored 15, notching double figures for the first time in four games after going scoreless in the Terps’ last two contests.

But Maryland’s offense faded in the second. Smikle, the Terps’ leading scorer, missed all four field goals she attempted in the frame. The junior ended the half 0-for-8 from the floor.

Maryland ended the final two minutes of the half on a 6-0 scoring run after falling behind by seven, its largest first-half deficit The Terps scored just 14 points while shooting 28 percent from the floor, allowing USC to take a 35-34 halftime lead. Watkins tallied seven more points to lead all scorers in the second frame and Iriafen netted six.

“A lot of plays we tried to take difficult shots, and that’s [how USC] set us up,” coach Brenda Frese said.

Smikle didn’t take long to net her first field goal after the break. The guard connected on a jumper and put away an uncontested layup in the opening three minutes of the half.

[No. 8 Maryland women’s basketball stays unbeaten with 78-61 win over Rutgers]

The Rutgers transfer then stole the ball from Watkins, her sixth turnover, and went the length of the floor for another layup to give Maryland its first lead in 10 minutes.

But the Terps couldn’t extend their advantage during the Trojans’ four-minute stretch without a field goal. A three-point play from USC guard Kayleigh Heckel tied the score at the end of the quarter, 58-58.

Maryland opened the final period on a quick 6-0 run as Sellers, Smikle and McDaniel each scored. But the Trojans answered with seven consecutive points of their own, eventually tying the game, 68-68, with under four minutes left.

Iriafen’s layup and ensuing free throw gave USC a three-point lead, 75-72. Poffenbarger attempted a 3-point shot from the corner, but her attempt clanged off the rim. The Terps scored two points in the final 2:41.

The Trojans scored nine straight in that span, with five from Iriafen who finished with 21. Maryland gave up its most points in a Big Ten game this season in its first defeat. USC was just the first of many big tests for the Terps — three of their next five games are against top-10 opponents.

“Just didn’t make enough plays down the stretch,” Frese said. “I thought Shy showed what a tremendous senior leader she is and a big-time player. … Loved seeing Chris get her swag back. We really needed to be able to have her tonight, and as we move into the stretch … against top-10 teams.”