PITTSFORD – Cierra Dillard didn't beat top-seeded Penfield on Monday night. It was her supporting cast who came up big to lead fourth-seeded Gates Chili to a 40-37 upset in the Section V Class AA girls basketball semifinals.

The All-Greater Rochester guard scored 12 points —16 below her average — but backcourt mate Samantha Heiler had the game of her life. The senior shooting guard pumped in 15 points, nearly double her average, scoring all of her baskets on 3-pointers. She hit three in the game-altering third quarter, when the Spartans (16-5) outscored the Patriots 17-7.

When junior guard Dejay Johnson drilled a 3-pointer with 30 seconds left in the period, Gates Chili's fans were rollicking at jam-packed Pittsford Sutherland High, and the Spartans had their first lead, 33-31.

The defending champion Spartans (16-5) will play No. 2 Rush-Henrietta (18-2), a 55-40 winner earlier over No. 3 Irondequoit, in Friday's championship.

"Basketball's a team game. A lot of people would say, 'The pressure's on Cierra. The pressure's on Cierra.' But my teammates did this for me," said Dillard, the UMass-bound senior has 2,051 career points. "I'm just so glad to pull it off with these great teammates."

The game was a rematch of the past three sectional championships. Penfield (17-3) won in 2012. Gates won in 2011 and last year. But the Spartans lost AGR picks Kori Bayne-Walker and Diona Johnson off that squad, leaving Dillard to carry the load.

"I'm so proud of them. We've been saying since Day 1, 'It's not all about Cierra. Everybody else has to step up,' " Gates coach Tara Graziadei.

Penfield had a chance to tie. It inbounded the ball with 2.2 seconds left. Margot Hetzke's good look at a 3-pointer was on line, but hit the front rim. "It felt pretty good coming off," she said.

The Siena College-bound forward led her team with 20 points. She finished her five-year career with 1,924. Senior guard Lucy Covley was held to four points and 6-foot-2 sophomore forward Emma Guy seven. Guy scored six in the first quarter, but picked up her third foul late in the half, then got her fourth late in the third quarter. She fouled out trying to block Dillard's putback with 3:52 remaining.

"Game-changing," Graziadei said.

Penfield led 31-24 with 2:25 left in the third after two straight Hetzke 3s, but Heiler and Johnson's 3s as part of a 9-0 quarter-ending push put Gates ahead. "Sammy can knock down shots," Graziadei said.

The Patriots paid so much attention to Dillard on defense, it left Heiler open. Her 3 from the right baseline with 4:33 left to play gave Gates the lead for good, 37-35. "It's a thrill. It's a rollercoaster," she said. "I love these girls and I'm so thankful I can play with them."

Dillard and Sedria Thomas missed the front end of one-and-one free throws with 1:50 and :20 left, but Penfield couldn't convert. Jessica Oechsle's two free throws with 4.4 seconds left for Gates made it 40-37, forcing Penfield to try a 3 on its last trip.

Hetzke was called for a carry with 1:14 to go. Covley missed a jumper at :27 and after a timeout, Hetzke missed a tough 12-footer with eight seconds left. "If you'd have told me (Dillard) would have only 12 and they would score 40, I would have thought we'd have won by 20," coach Mark Vogt said.

In the first semifinal, R-H's superior height at nearly every position was key. The Royal Comets, who feature 6-foot junior forwards Dana Watts (19 points, 14 rebounds) and Emily Nestler (13 points, 8 rebounds), hurt Irondequoit on the offensive boards, especially in the third quarter. Senior Zana Dillard added 10 points and 10 rebounds.

"We didn't lose the game on offense, I thought it was our defensive effort and giving up second shots," said Irondequoit coach Katie Decker, whose team gave up 20-plus offensive boards.

The Eagles (16-5), last year's Class AA2 champions, also lost 54-41 to R-H in early December. Watts scored nine in a 14-4 third-quarter surge that included an 11-0 run that R-H control for good. The Comets' size in a stretched out zone also made it difficult for Irondequoit to score.

Junior guards Savannah Crocetti and Abby White and senior forward Jenn Reininger are all 5-7 or shorter. Crocetti scored nine points in the first half, but before she scored in the second R-H was up 44-27 early in the fourth quarter.

"Crocetti had three 3s in the first half and we said we've really got to make sure we get out on her," R-H coach Steve Shepanski said.

Crocetti had 13 points, but Reininger (nine) and White (one) were held below their averages (11 points).

JDIVERON@DemocratandChronicle.com

Twitter.com/@RocDevo