The Matadors scored eight times in the eighth inning and right-hander Vale Lopez made it stand up as Northridge advanced into the national championship game, 8-6.
Northridge's opponent will be the winner of today's game between the University of Tampa and Jacksonville (Ala.) State.
Through seven innings, Lewis (49-14) was well on its way to defeating Northridge.
The Matadors (32-21), who scored 36 runs on 49 hits in their first two series games, had only three singles--all by Eric Johnson--going into the eighth.
Scott Sharts, Division II home run leader, hit a three-run homer over the scoreboard in left field to put Northridge ahead.
Sharts' 28th home run of the season came one pitch after a foul ball down the right field line that should have been caught.
"It always seems to happen like that," Northridge Coach Bill Kernan said. "You just don't give a hitter like Sharts a second chance."
Northridge's other runs came on a two-run triple by Andy Hodgins, an error, a wild pitch and a passed ball.
Lopez allowed 10 hits in his second win over Lewis in five days. He has won his last nine decisions.