The fourth act of a play is often referred to as the resolution or the finale.

In its fourth matchup of the season against Shady Side Academy, Greensburg Central Catholic was sharp from the second the curtain went up until it took its final bow in a surprisingly one-sided Western final.

Executing a near flawless game plan, GCC raced past the Bulldogs, 49-27, in the PIAA Class 3A semifinals Monday night at Norwin to advance to the state championship for the first time since 1997.

The Centurions will play District 2 runner-up Holy Redeemer (22-8) in the championship game at 6 p.m. Thursday in Hershey.

“Amazing,” GCC coach Chris Skatell said of his team’s performance. “This is awesome for these girls. I felt we could win after we had a great week of practice. The girls were ready to go.”

GCC (23-7) was as clingy defensively as it was efficient on offense, using multiple zone defenses to take the Bulldogs (26-3) out of their rhythm in the latest chapter of the rivalry.

The Bulldogs, who had won 17 straight games, won the three previous matchups against the Centurions. Unlike GCC, they had been tested in the state bracket. They needed overtime to get past Marion Center (63-54) and narrowly escaped Beaver Falls, 39-33.

GCC’s margin of victory in the state playoffs is 25.5 points after its fourth straight double-digit victory.

Shady Side Academy, which beat GCC in the WPIAL championship this year, 57-40, and was the PIAA runner-up last year, was limited to one field goal and five points in the second half.

GCC outscored the Bulldogs 23-5 after halftime.

“Defense,” GCC senior guard Erica Gribble said. “We won with defense. The pressure was on them to beat us four times, not on us to beat them one time.”

Junior Avery Jones scored a game-high 16 points, 12 in the second half, while junior Morgan Skoloda had nine, senior Jayla Peterson eight and Gribble seven for GCC, which finally broke through after reaching the semifinals three times in the last four years.

Gribble, the high-scoring Richmond commit, focused more on defense and passing. GCC had played the Bulldogs man-to-man in all of their previous meetings.

“We asked Gribs to guard Karis (Thomas) for 32 minutes on a big floor (at Pitt) and that is a lot to ask,” Skatell said. “We said, let’s try some zone — 3-2, 2-3, 1-3-1 chaser — and take away their looks.”

As a result, Shady Side Academy’s key scorers were drastically limited. Seniors Karis Thomas and 6-2 Cassie Sauer had five and four points, respectively. The former could not get to the basket, the latter could not post up.

Sauer injured her right wrist at the end of the first quarter but quickly returned with tape on her wrist and hand. She struggled to gain position against Jones and Abby Dlugos.

Thomas, a Purdue Fort Wayne commit who had 21 points in the WPIAL final against GCC, had one field goal this time, a deep 3 late in the second quarter.

Freshman Morgan Kane led the Bulldogs with nine points. Sophomore Kate Benec hit two 3s for six.

“We planned on playing a zone because they hadn’t seen it before,” said Skoloda, who hit three 3-pointers. “We wanted to get the ball to each other and play as a team.”

GCC led 14-12 after the first quarter as Gribble and junior Nolan Althof made 3-pointers.

The Bulldogs went ahead 17-14 on a layup off a steal by Kane. But Skoloda tied it with a 3.

After GCC went ahead by five (22-17) on a Skoloda 3, Thomas hit from deep to tie it 22-22 with 2 minutes, 28 seconds left in the second quarter.

Shady Side Academy, however, didn’t make another basket that wasn’t a free throw until Kane scored with 4:13 left in the fourth.

While the Bulldogs labored to get open shots, GCC was busy moving the ball crisply around the key and scoring in close.

“We scored five points in the second half,” Shady Side Academy coach Jonna Burke said. “Credit their defensive game plan; it was strong. The (zone) was not something we expected. The looks we got were tough looks. We missed some shots in close and we missed foul shots. We didn’t move the ball quickly enough. It was not our night.”

The Bulldogs were 6 of 15 on free throws.

GCC went on an 11-1 run after Thomas tied it and stretched the advantage to 10 (33-23) on a jumper by Jones, methodically pulling away in the second half.

Skoloda’s 3 beat the third quarter buzzer and made it 36-25.

Jones scored 10 of her team’s 12 points during one stretch, taking a feed from Dlugos and finishing to make it 40-25.

Jones returned the favor soon after and Dlugos’ basket gave GCC a 43-27 advantage.

Jones has scored in double figures in every playoff game this year.

“We stayed together and that’s when we play our best,” Jones said.

The loss ends the brilliant careers of Thomas, Shady Side’s all-time scoring leader, and Sauer.

“GCC played well, but the most upsetting part for me is not getting to see these kids at practice anymore,” Burke said. “(The seniors) never lost a section game, had two WPIAL championship appearances and won one and made the state finals. It’s tough to see it end.”