They say it is difficult to beat a team three times in a season.

It is even harder to get to the WPIAL finals three straight times.

Many WPIAL basketball players get to go to the “Pete” only when they buy a ticket.

But Norwin senior guard Ava Christopher is as grateful as she is thrilled to have earned a third straight trip to Petersen Events Center to play for another WPIAL title.

A determined Christopher piloted a strong defensive effort by the No. 2-seeded Knights, who nearly pitched a shutout in the fourth quarter, on the way to a 46-28 semifinal victory over No. 3 Upper St. Clair — the team they lost to in last year’s championship — on Tuesday night at Keystone Oaks in Dormont.

“Each year it gets a little better,” said Christopher, who scored 18 points, including three 3-pointers, for Norwin (19-4), which will face No. 1 Canon-McMillan (20-4) in the Class 6A final at 5 p.m. Saturday. “This was my best game back.”

Canon-McMillan held back No. 5 Seneca Valley, 47-42, in the other semifinal. The Big Macs will play in their first WPIAL final.

Norwin and Canon-McMillan split two games in section play, with the Knights losing 44-37 at home to miss out on a section title.

Christopher missed 10 games with a knee injury — her brace gives it away — but returned in time to help the Lady Knights make a run at their second WPIAL title in three years and fourth overall.

Her determination was evident in her play. She scored 10 in the second quarter to put Norwin ahead to stay as it defeated the Panthers (12-12) for the third time this year.

“I wanted this,” Christopher said.

The most seasoned Norwin player guided the way in Norwin’s fourth straight semifinals appearance.

“Ava has been waiting to have a breakout offensive game like that,” Norwin coach Brian Brozeski said. “She knows what it takes to get here.”

Upper St. Clair didn’t score in the fourth quarter until senior guard Ryan Prunzik swished a 3 with 7.6 seconds left. It snapped a scoring drought of more than seven minutes.

That came well after a close first quarter where Norwin clutched a 13-11 edge after Prunzik scored six straight points to close the frame.

In between, the Lady Knights built a 30-18 halftime lead and led 39-25 after three.

Seven players scored for Norwin, including junior Liz Yarosik, who had 10. Sophomore Nia O’Barto had six.

After a 17-point second quarter, Norwin managed only 16 in the second half. Still, the Knights never wavered with their ultimate goal in mind.

“It wasn’t perfect,” Brozeski said. “We’re a team that prides ourselves on having multiple scorers at any time.”

Norwin took control in the second quarter as a three-point lead swelled to 12 by halftime thanks to an 11-2 run. During the surge, Christopher hit two 3s, and sophomore Lenyn Brozeski make one.

“I am really pleased with our effort,” Brian Brozeski said. “Prunzik is a great player, and she played her heart out. Truthfully, I’m glad she made that last shot because she competes so hard.”

Lenyn Brozeski hit 5 of 6 3s against Hempfield in the quarterfinals. She was 2 for 2 in the semis.

Norwin made six 3s.

“Confidence is earned through preparation,” said coach Brozeski, Lenyn’s father. “I told her mother, keep feeding her the same dinner.”

Prunzik finished with 13 to lead the Panthers, who had only three scorers.

Junior guard Caroline Barnard added 11.

Upper St. Clair will host Seneca Valley (14-7) at 7 p.m. Thursday in the WPIAL third-place game.