The defending champion is out. So is the No. 2 seed. In one stunning upset, Mater Dei is history, a footnote to the 2011 Southern Section Division 1 baseball playoffs.
Esperanza took down the Monarchs, 5-1, on Friday in the section quarterfinals.
The Aztecs (22-10) will play Long Beach Wilson (26-6) in the semifinals Tuesday at Blair Field as part of a doubleheader. Wilson defeated Simi Valley, 2-0.
The other semifinal will include Lakewood — which defeated top-seeded Edison, 3-1 — against Riverside North, a 6-2 winner over Dana Hills. None of the remaining teams were seeded in the top four.
Esperanza pitcher Austin Pettibone didn't give up a run until Jeremy Martinez homered in the seventh inning. for Mater Dei (24-6).
Pettibone (8-4), who was staked to single runs in the first and second innings and three in the third, pitched a four-hitter and struck out seven.
Nick Catalano led off the bottom of the first inning with a home run for Esperanza, which had lost two of its last three games heading into the playoffs. Esperanza, which had hit three home runs coming into the playoffs, have now hit four in three games.
The Aztecs defeated Capistrano Valley, 10-2, and Newbury Park, 20-9. Now, they have bagged their biggest trophy to reach the semifinals for the first time since 2007 when they lost to Wilson.
Kevin Viers had three hits, an RBI and scored a run. Brad Anderson, Mitch Christensen also had RBIs.