EVANSTON - For the second straight day, the Illinois State softball team could not preserve an early lead against No. 6 Northwestern. This time, that inability ended the Redbirds' season.

The second-seeded Wildcats capitalized on Stacy Birk's wildness in a three-run fifth inning en route to a 4-1 victory over No. 25 ISU in the championship game of the Evanston Regional on Sunday at Sharon J. Drysdale Field.

The Wildcats (48-11), who lost to Arizona in the 2006 Women's College World Series finals, advanced to face South Carolina next weekend in a best-of-three Super Regional, with the winner earning a World Series berth.

The Redbirds, who finished the season at 44-17-1, took a 1-0 lead in the third inning when Birk scored on a fielder's choice. But ISU could not generate any more offense against the Wildcats' Eileen Canney, who improved to 29-9 by limiting the Redbirds to three hits while striking out 11 batters.

Northwestern tied it quickly when Nicole Pauly drew a leadoff walk from Shannon Nicholson, took second on a wild pitch and scored from third on a bizarre two-out single by Jessica Miller.

Miller hit a little flare beyond the outstretched arm of ISU third baseman Kara Nelson and the ball deflected off the glove of a diving Kaprice Williams into foul territory. But Miller fell flat as she tried to leave the batter's box and had to scramble to her feet and sprint to first to beat the throw.

Nicholson (21-8) found more trouble an inning later. Katie Logan ripped a one-out double off the top of the fence in right, then scored on Tammy Williams' single through the right side of the infield.

Birk relieved Nicholson and threw a wild pitch on her first delivery. She then hit Garland Cooper with a pitch and allowed both runners to move into scoring position with another wild pitch. Pauly followed with a two-run single up the middle to pad the Northwestern lead.

Birk scored ISU's run after drawing a leadoff walk in the bottom of the third inning. After Casey Gorrell followed with a single to put runners on the corners, Jackie Williams hit a dribbler to shortstop. The Wildcats' Tammy Williams threw to the plate, but catcher Erin Dyer could not tag the sliding Birk.

ISU looked to add to its lead with two on and no outs. Kara Nelson hit into a force play at second that put Redbirds on the corners, then stole second to give ISU two runners in scoring position. But Canney escaped further damage by striking out Tiffany Prager and getting Amber Smith to pop out to short.