Between an onslaught of big second-half 3-pointers and a remarkable performance from the foul line, Indiana did everything it could to push the No. 2-ranked and top-seeded USC women's basketball team in the Big Ten quarterfinals Friday.

But the Trojans pushed back even harder, responded each and every time they were challenged on the way to finishing off a highly-entertaining 84-79 win over the No. 9-seeded Hoosiers at Gainbridge Fieldhouse in Indianapolis.

Star JuJu Watkins poured in 31 points, 10 rebounds and 3 steals and forward Kiki Iriafen came up big with 21 points and 10 rebounds to lead the Trojans (27-2) over the Hoosiers (19-12) and into a Big Ten semifinals matchup Saturday at 12 p.m. PT vs. the winner of No. 5 Michigan (22-9), which advanced with a 98-71 win over No. 4 Maryland on Friday.

USC, meanwhile, was without starting center and leading rebounder Rayah Marshall due to illness, but the Trojans' supporting cast came up big as Avery Howell chipped in 10 points and 4 rebounds, Kennedy Smith added 9 points and 7 boards and Talia von Oelhoffen had 6 points and 5 assists -- all of which felt momentous.

"We knew this was going to be work. We knew this was going to be a tough one," coach Lindsay Gottlieb said. "Indiana's a really good team. They're an NCAA tournament team. ... For us, I'm really proud of our group. We found out right before the game that Rayah couldn't go and everyone stepped up. I thought we played really hard. I think Indiana poses some issues for us guarding them because they do so much action, but our two All-Americans played like All-Americans and I thought a number of people stepped up and that's why we've become the team that we've become."

The Trojans could never rest easy in this one as Indiana made 25 of 27 free throws on the day and was 5 of 11 on 3-pointers in the second half to keep the pressure on the regular-season Big Ten champs.

"It was a gritty one," Watkins said. "Indiana is a great team to play. They come out with a lot of energy, so it was only right that we matched that and even more."

After leading 38-34 at halftime, USC saw that advantage erased early in the third quarter when Indiana reeled off 8 straight points, including 6 from Shay Ciezki, to take a 42-40 lead.

But as would be the story of the game, every time the Hoosiers challenged USC, the Trojans responded.

After trading the lead back and forth, von Oelhoffen hit the first of her two huge 3s to put USC up 48-46 midway through the third quarter.

The Trojans never trailed again, but they also couldn't pull away until the very end either.

Yarden Garzon, who hit 5 of 10 3s on the way to a team-high 23 points for Indiana, knocked a 3 down at the end of the third quarter to keep it close at 59-57, made another 3 early in the fourth quarter to cut the USC lead to 62-60 and soon followed with a layup to keep it close at 64-62.

The Trojans gained some separation when Iriafen followed with a turnaround mid-range jumper -- she was potent in the mid-range game all day -- and Howell dropped in a fastbreak 3-pointer on a feed from Watkins for a 69-62 lead.

But Ciezki later hit a 3 for the Hoosiers, then blocked Watkins at the other end and Lilly Meister got to the line for Indiana for 2 free throws to cut the Trojans' lead to 71-68 with 3:30 to play.

Right on cue, von Oelhoffen drained a 3 from the right wing to make it a 6-point lead, and after a miss on the other end Watkins hit a 3 as well to push it to 77-68 with 2:42 to play. The game never got closer than 4 points (in the final seconds) the rest of the way.

USC is vying for its second straight conference tournament championship after winning the Pac-12 tournament last year. The Trojans, who moved to No. 2 in the AP rankings this week for the first time since 1984, are also polishing off their resume for a No. 1 seed in the upcoming NCAA tournament.

For Watkins, the newly-minted Big Ten Player of the Year, this was her 21st-career 30-point game in just two seasons of play.

"It's early in her career to talk about the overall greatness, but I think she has that sort of something you can't really describe," Gottlieb said. "You see the best athletes get to another level. ... That inner something that makes her such a winner has been there from Day 1, and everyone else feeds off that and I think that's something that's really impressive."

Said Watkins of the history she continues to make early in his career: "I don't really think about it much, if I'm being honest. I just go out there and play for the team and whatever's needed of me I do. But yeah, I think it's just a testament to the long nights in the gym and a team and a coach who really trusts in me, so I'm able to play to the best of my ability."

Gottlieb, meanwhile, said she was hopeful Marshall, the steady 6-foot-4 senior who averages 7.4 points and 8.6 rebounds per game, might play Saturday.

"I mean Rayah is a leader for us. She's had an incredible season, she's a great player, we always want her on the floor. But we found out shortly before the game that she couldn't go. She's battling an illness and it just prevented her from being able to go, so hopefully we get her tomorrow," she said. "But we also have a lot of trust in our entire team. You always want to go in at full strength, but I think you also want the team to be ready to do what they need to do. I think two things happened because she was out -- we started small and played Kiki at the 5 and went four guards, and then we came in with Clarice [Akunwafo] who I thought gave great minutes as well."

USC defeated semifinals opponent Michigan, 78-58, at home in late December in the teams' only regular-season meeting.