Harrison, Simmons, Graves lead Lady Vols past LSULSU forward Shanece McKinney (21) blocks a shot by Tennessee forward Bashaara Graves during the first half in an NCAA college basketball game in the quarterfinals of the Southeastern Conference women's tournament, Friday, March 7, 2014, in Duluth, Ga.(AP Photo/John Bazemore)
DULUTH, Ga. (AP) -- Nothing was going right for Meighan Simmons, so the Tennessee star decided to stop being hard on herself.
''I was very proud about how my teammates stepped up,'' she said. ''They lifted me when I got down on myself, when I felt like I wasn't doing things right.''
Isabelle Harrison scored 21 points, Simmons and Bashaara Graves each added 14 and No. 6 Tennessee used an overpowering late run to beat LSU 77-65 in the quarterfinals of the Southeastern Conference tournament on Friday night.
The second-seeded Lady Vols (25-5) have won five straight and 11 of 12. Tennessee will face the Texas A&M-Auburn winner in the semifinals.
Theresa Plaisance finished with 21 points and Danielle Ballard scored 15 for LSU (19-12). The Lady Tigers, seeded 10th, have lost seven of eight.
Tennessee's 19-0 run late in the second half made it 70-55 lead on Simmons' two free throws, but the game's first 35 minutes were tough on the fifth-leading scorer in school history.
''We're not going to tell her not to shoot the basketball,'' Lady Vols coach Holly Warlick said. ''When she's not in her rhythm, we're going to get her to spread the ball around. Right now she plays within the team. She understands the importance of the defensive end. It's a mindset for Meighan. ''
Simmons, who had averaged over 22 points in the previous three games, was just 3 for 16 from the field before her reverse layup from the baseline ended a fast break to force a 55-all tie.
''To be honest with you, the coaches were getting on me about continuing to shoot the ball,'' Simmons said. ''Holly was telling me to get it on the defensive end, stay within the system. Finally after a while, I got a couple steals, some assists later on in the game, some good defensive stops later on.''
Harrison followed with a runner over Plaisance to make it 57-55 and give the Lady Vols their first lead since 4-3 and bring the large contingent of cheering Tennessee fans to their feet at the Gwinnett Arena.
With 12 rebounds, Harrison recorded her 16th double-double this season, but she credited Plaisance for making the Lady Vols work hard to beat her.
''She can play outside and inside,'' Harrison said. ''Being in the post, sometimes it's hard to adjust to players like that. I really wanted to get focused. I knew when she was going off, so I made a commitment to myself and the team that I was going to lock her down.''
Tennessee finished second in the SEC regular season to No. 5 and top-seeded South Carolina, a 67-48 winner over Georgia.
Trailing 4-0, LSU went on a 27-8 run, ending with Jeanne Kenney's third 3-pointer, to take a 15-point lead with 9:29 left in the first half.
Plaisance had 14 points to help the Lady Tigers take a 34-22 lead, but Tennessee closed to within six at halftime.
The Lady Vols chipped away at the lead before Cierra Burdick's layup forced a 43-all tie.
LSU coach Nikki Caldwell called timeout to try and settle down her team, and Plaisance followed with a 15-footer on the ensuing possession and a straightaway 3 that made it 48-43 with 11:54 remaining.
But the Lady Tigers couldn't overcome getting outscored 52-18 in the paint and 25-5 on turnovers.
''They were just doing a great job taking away basically everything from me,'' Plaisance said. ''After I hit those first couple of shots, they denied me really hard. I got a back door. After that, it was almost impossible to get the ball inside.''
LSU also struggled with inconsistent shooting. After beginning the game 10 for 16, the Lady Tigers missed 27 of their next 37 shots.
Tennessee junior point Ariel Massengale missed her 11th straight game since getting hit in the face during a 20-point win over Florida on Jan. 23. She sat on the bench, but was not expected to play this weekend.