PORTLAND — Sara Warnock had already given her team a huge boost at the offensive end. Now it was time for one more stop.

With Greely leading by three points and the seconds ticking down, Warnock was pretty sure Mountain Valley would look for its own star to take a final shot.

Warnock contested Ayla Allen’s 3-point attempt and the fifth-seeded Rangers held on for a 42-39 victory against fourth-ranked Mountain Valley in a Western Class B girls’ basketball quarterfinal Tuesday night at the Portland Expo.

“I had a pretty good idea (Allen) would be shooting it,” Warnock said. “So we really made sure that she was the one we would be focused on.”

Greely (15-4), a Western Maine finalist the past two seasons, will face top-ranked York (19-0) in the semifinals at 4:30 p.m. Thursday at the Cumberland County Civic Center.

Mountain Valley (14-5) closed the third quarter on an 11-2 run to take a 31-30 lead.

On the first possession of the fourth quarter, Warnock passed up an open shot in the paint and dished outside the arc to Caroline Hamilton.

“I mean, (Hamilton had) been on all night and I had missed more than she had, so I thought she would be a good option,” Warnock said.

Hamilton buried the 3 to put Greely back in front.

Then Warnock asserted herself. First came a strong offensive rebound and putback with a Mountain Valley player draped across her arm, leading to a free throw. Warnock made two more free throws after getting fouled, then converted a rebound for another bucket to give Greely a 40-35 lead.

“Sara has been our steadiest player, and what you saw was a senior who didn’t want to lose,” Greely Coach Bill Goodman said. “I said, ‘I need rebounds,’ and she went and got them for me. She’s a tough kid and she really showed it in the second half.”

Mountain Valley was limited in its options, in part because Allen (14 points) was struggling with flu symptoms.

“Ayla was working her tail off on defense and at the same time battling the flu. She was down there (in the locker room) throwing up at halftime,” Mountain Valley Coach Rich Allen said.

The Falcons got a huge boost in the closing minutes from their smallest player on the court, 5-foot-3 senior guard McKenzie Paterson.

On consecutive possessions, Paterson came up with offensive rebounds (the second time on her own miss), and converted them into four points, cutting the Greely lead to 40-39.

With 1:10 to play, Greely worked the clock for 40 seconds before Megan Coale missed a 3-point attempt. Mountain Valley freshman Brandon Roberts got open for a good interior shot that rolled off the rim. Greely sophomore Caton Beaulieu, who had taken one shot all game, grabbed the rebound, was fouled and calmly made both free throws.

“We had a great opportunity to win the game at the end and unfortunately we came up short, but I give the kids all the credit,” Rich Allen said.

Both teams used the 3-point shot as a primary offensive option in the first half.

Greely was 4 of 12, with Hamilton (14 points) making 3 of 6 to lead all scorers with 11 points at the half. Mountain Valley connected on 4 of 10 — Allen was 3 of 6 — but didn’t make a basket from inside the arc while falling behind 21-16.