BATON ROUGE, La. (AP) -- LSU coach Nikki Caldwell figured an 18-point lead against a Green Bay team that hadn't lost in more than three months was too good to be true.
She believed, however, that her players would at least have the composure to respond when the Phoenix made that one last, blood-pressure-spiking run that she sensed was coming.
Danielle Ballard and Theresa Plaisance capped a 16-point performances by hitting clutch free throws in the final 15 seconds, and LSU held off Green Bay 75-71 Sunday night in the first round of the NCAA tournament.
''When we got our lead I literally thought, 'This is too soon, because this isn't us,'' Caldwell recalled. ''We're not that team that has blown anybody out.
''But if it did get to late-game, I saw a team that knew how to play down the stretch,'' she added. ''It seemed to me that they had the composure, they had the confidence, to really finish off this game against an opponent that was bringing everything at them.''
Adrienne Webb added 15 points and Bianca Lutley 13 for sixth-seeded LSU (21-11), which saw its lead dwindle to three in the final minute before surviving to meet Penn State on Tuesday night in a rematch of the second-round meeting that the Lady Lions won in Baton Rouge a year ago.
Sarah Eichler hit four 3-pointers and scored 22 for No. 11 seed Green Bay (29-3), the Horizon League champion, which had its 24-game winning streak end as it was bounced from the tournament in the first round for the first time since losing to LSU in Baton Rouge in 2009.
''It's really hard to go out like this,'' said a tearful Adrian Ritchie, who had 16 points but fouled out with 3:05 left. ''We won every single first-round (game) of our career so to go out like this is a little bit bitter-sweet."
Jenny Gilberston added 15 points and Lydia Bauer 11 points for Green Bay.
Known for its 3-point shooting, Green Bay hit 12 of 28, with Gilbertson and Bauer hitting three apiece.
But LSU was more efficient from deep, attempting 14 3s and hitting nine, including one which Plaisance hit off the glass.
''The 3-point game really hasn't been our strength this season at all,'' Plaisance said. ''I think some of these shots were a bit lucky. ... Webb did a great job of coming out early in the second half and knocking down a few.''
LSU also had to withstand the loss of guard Jeanne Kenney, who was carried off the court holding a towel to her face in the final minutes after a collision with Webb. She appeared to hit her head and it wasn't clear if she'd be ready to return for LSU, which was already down to eight healthy players, by Tuesday.
Both teams shot 49 percent and had 29 rebounds each in what turned out to be an evenly matched game, even though it didn't look that way throughout.
Webb hit three 3s and another jumper early in the second half, sparking an 18-5 run that put LSU ahead by 17 points at 49-32.
Green Bay coach Kevin Borseth said his defensive game plan was to force LSU to from 3-point range, where the Lady Tigers had shot 27.8 percent all season, and it simply backfired.
''When they lock up inside, you've got to knock down the outside shot,'' Webb said. ''Theresa did a very good job of that, Bianca did.''
LSU led by as many as 18 when Plaisance followed her banked 3 with a putback to make it 54-36 with a 12:38 to go.
The Phoenix made a game of it by pressing defensively and hitting 3s in bunches.
Ritchie ignited the comeback when she scored as she was fouled.
''We tried to rally as much as we could,'' Ritchie said. ''We fought as hard as we could because that's who we are.''
Then Ritchie, Gilbertson and Eichler hit consecutive 3s to cap a 12-2 run which cut it to 65-61 with 5:06 to go, and Caldwell, a former player at Tennessee called timeout.
''I talked to them about being a player,'' Caldwell said. ''I said, 'We're tight right now and we're playing that way, and you've got to play this game loose.'''
Lutley responded with a clutch 3 and added another three-point play on a driving layup as she was fouled.
''Bianca is an all-round athlete,'' Plaisance said. ''She can take the drive, take the 3, post up, basically everything.''
Still, Green Bay got as close as 72-69 after Megan Lukan's 3 with 49 seconds left.
A critical offensive rebound by Ballard extended a late LSU possession that ended with Plaisance's free throws after Green Bay fouled her intentionally, but Lukan once against made it a three-point game with 9 seconds left.
LSU then was able to get the ball to Ballard, who made a free throw to virtually seal it.