Rennie, a senior quarterback who has been with the West program since its 0-14 campaign in 2006, had her hand in all five West touchdowns as the Eagles raced out to a 25-0 lead and never looked back.
"I've been playing since it started, and I really want to get to the championship," said Rennie, the conference's Defensive Player of the Year.
Rennie threw three touchdown passes, ran for another and returned an interception for a touchdown for West (7-8), which lost both times to South (7-8) during the regular season.
"We certainly weren't looking past them because we knew they were a good team, but we definitely knew we were capable of beating them," said South coach Melanie Sugita. "They just played better than us tonight."
Rennie scored on a 2-yard run in the first quarter and hit Alison Jones with a 21-yard pass up the middle to give West a 12-0 lead before South could gain a first down.
On the Wolverines' next possession after the Jones score, Rennie picked off South quarterback Molly Nokelby's first pass attempt and raced into the end zone for a 17-yard touchdown return.
West outgained South 287-193, thanks in part to a defense that forced a pair of interceptions and kept the Wolverines off balance for most of the first half.
"I think that was the big difference in this game," West coach Travis Cantrell said.
After forcing the fourth South punt of the half, Rennie went back to work, hitting KeiAndrea Mathews with a 5-yard scoring pass that was set up by a 30-yard strike from Rennie to Jones.
West used a no-huddle offense to keep South on its heels, which Rennie said was a big key to the team's first-half success.
"They weren't able to get set," she said.
South got a 5-yard touchdown run from Heidi Pichler to cut the lead to 25-7 heading into the locker room.
The Wolverines got as close as 25-14 after Pichler caught a 12-yard pass from Nokelby on the first drive of the second half, and were on the comeback trail after Alexandra Brewster intercepted Rennie inside West territory.
South got as far as the West 14-yard line before West's Erin Willahan stepped in front of Nokelby's pass attempt on the final play of the third quarter.
The Eagles then marched 88 yards on eight plays, getting a 31-yard pass from Rennie to Jones to seal the deal.
"That was kind of the nail in the coffin," Sugita said.
The victory moved West into today's semifinal round, where they'll play Dimond at 6 p.m. at The Dome. The Lynx won 41-0 over Eagle River on Thursday. Dimond beat West twice during the regular season, but the Lynx needed a touchdown in the closing seconds to get by the Eagles 20-18 last week.
While the Lynx are the tournament's top seed, Rennie said Thursday's win proves the Eagles have what it takes to advance to the finals -- and beyond.
"We're not afraid of them," she said.
Find Matt Tunseth online at adn.com/contact/mtunseth or call 257-4335.
Dimond 41, Eagle River 0
Top-seeded Dimond (14-1) had three interceptions, including two that were returned for touchdowns, in a first-round victory over Eagle River (0-15).
Keiahnna Engel carried the ball five times for 99 yards and a touchdown and also returned an interception 99 yards for a score for the Lynx.
Kimmy Jackson ran eight times for 75 yards and a pair of scores. Gabby Coleman added an interception return for a touchdown and Vanessa Youngmon had four pulls and a pick.
Dimond will play West at 6 p.m. in one of tonight's two semifinal games at The Dome.
Bartlett 25, East 0
Tiffani Pollard ran for a touchdown, threw for a touchdown and caught a touchdown pass to lead No. 2 seed Bartlett (12-3) past East (3-12).
Destiny Little had a pair of picks and caught a touchdown pass from Pollard.
Yollie Alailefaleula threw touchdown passes to Pollard and Trina Foilefuto. Pollard also had an interception.
Bartlett will face defending conference champion Chugiak at 7:30 p.m. at The Dome with a berth in the conference championship game on the line.
Chugiak 19, Service 0
Kendra Bulawa ran for 110 yards, including a 3-yard touchdown run, and returned a punt 38 yards for a score to pace the Mustangs (12-3).
Kendra Harter added a 3-yard scoring run and Kim Roberts grabbed seven flags.
Service ended its season at 5-10.
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