SAN PEDRO >> Marina and San Pedro faced off Tuesday for a chance to continue their surprising postseasons and claim the right to represent Southern California for the first time at the California girls basketball championships.

The Vikings seized the opportunity.

Senior point guard Tiana To scored 19 points and added seven steals and freshman guard Rylee Bradley scored 14 points as Marina defeated San Pedro 51-43 in the Division V final of the CIF Southern California Regional playoffs at San Pedro High.

The Vikings (21-15), who went 6-20 last season, will play in the CIF State final against the Fall River-Bret Harte winner on either Friday or Saturday at Golden 1 Center in Sacramento. Fall River, of Shasta County, was the top seed in the CIF Northern California Regional playoffs while Bret Harte, from Angels Camp, was seeded third.

“We’re underdogs,” said To, who opened the game with a 3-pointer and took a key charge in the fourth quarter. “Everybody has counted us out. Hard work, teamwork. All together. This is all of us. It’s the best feeling in the world.”

No. 2 San Pedro ( 24-9) served as the host Tuesday as the higher seed in the south regional, but No. 8 Marina quickly asserted itself.

The Vikings led 25-19 at half behind 10 points and five steals by To.

Their aggressive defense, including a full-court press, forced 15 turnovers and helped the Wave League team lead by as many as eight.

San Pedro trimmed the lead to 31-28 in the third, but To sank a 3-pointer to spark a 9-0 run. The Vikings capped the run with sophomore Maria Tejeda diving for a loose ball and passing to Bradley, who fed To for the layup.

Marina sophomore Sydnie Smith sank a clutch 3-pointer in the fourth to help secure the victory. She finished with nine points.

Junior point guard Noelani Raigans scored 13 points to lead San Pedro. Shalia Coleman and Madison Adrid each added nine points.

The Pirates and fourth-year coach Kevin Simpson reached the regional final after claiming their first L.A. City Section title since 1986. The Pirates needed to win Division II to qualify for the regional and edged Chatsworth 52-51 in overtime.

Marina showed dramatic improvement this winter, emerging as the No. 10 team in the Division VAA poll before the CIF-SS playoffs. The Vikings reached the semifinals to qualify for regionals. They defeated No. 1 Gahr — which they lost to the semifinals — en route to the regional final.

The inspiration doesn’t stop there. Fifth-year coach Danny Roussel is a three-time Leukemia survivor.

“Who would have thunk (this run),” he said. “Finishing like this and being able to go play for a state championship is something beyond all of our wildest dreams.”