The oldest high-school athletic rivalry west of the Mississippi River will stir the blood of current students and alumni alike on Friday, when the Sunset District’s St. Ignatius College Preparatory and cross-town rivals Sacred Heart Cathedral Preparatory meet on the football field of Kezar Stadium. There at 7 p.m. they begin the opening round of the yearly contest for the Bruce-Mahoney Trophy, a memorial to two graduates — one from each school — who lost their lives in World War II.

The trophy’s namesakes are more recent, but the rivalry between the two schools dates back to 1893, when they met for a rugby match on St. Patrick’s Day. SH won that game, but in the years since the Bruce-Mahoney Trophy was introduced in 1947, SI has won it 44 times to SH’s 19.

The trophy is awarded to the school whose varsity boys teams win two out of the three meetings of the schools in football, basketball and baseball.

St. Ignatius enjoys a strong record of football victories over its rival — but this year, reports high-school sports website San Fran Preps, Sacred Heart’s record (4-4, 1-4) means the Irish are favored to win over the Wildcats (1-6-1, 0-5).

The Irish have been competitive all year in West Catholic Athletic League play, while St. Ignatius has struggled mightily. Still, [Sacred Heart head coach John Lee] is not willing to take the Wildcats lightly in a game that could not only earn the Irish bragging rights, but a CIF-Central Coast Section playoff bid.

“I’d be lying to say I didn’t want to go back to the postseason,” said Lee, who has won one Bruce-Mahoney game in his seven years at Sacred Heart. “Records go out the window [for this game]. I have to figure they’re going to think they’re going to be playing the spoiler. They don’t want to see their cross-town rival in the playoffs.”

The game is important for the Irish’s playoff chances, but Lee knows its impact on the communities of both teams.

“Not only is it important to the kids, it’s the alumni,” Lee said. “They come out of the woodwork for this game. I mean, guys from the ’40s and ’50s. It’s about the richness of our two schools’ traditions and the City and that goes into all facets of life.”

St. Ignatius also heads into the game without Steve Bluford. The Wildcats’ head football coach left his position with the team in October.

[SI interim head coach John Regalia] wouldn’t comment on how the team has been impacted by Bluford’s absence, but stressed the importance of the game.

“Obviously this one is a rivalry game and it’s a little different,” Regalia said. “Both schools understand the significance. The game speaks for itself.”

An audio webcast of the game starts at 6:40 p.m. Friday.

Photo: Tawnya Gray and AJ Canaria/San Fran Preps.