Muir senior forward Victor Lugo scored twice at the end, but time ran out on the visitors, who are also the Mustangs.
"I brought in the young guys just to get a taste of the playoffs at the varsity level," Cordoba said. "They got a little awakening, but overall I thought the guys played well, the starters played well. We moved the ball around, we created chances and we finished our chances. It was just a good start [to playoffs] for us."
Costa Mesa (9-9-4) grabbed a 2-0 lead at halftime. Junior Kevin Parra scored his second goal in the last two games in the 14th minute, after taking a pass from Cesar Pineda. In the 35th minute, junior midfielder Brian Delgadillo played the ball ahead to Sanchez, who found himself one-on-one with Muir goalie Peter Tapia.
Sanchez directed the ball into the left corner for the two-goal advantage.
Mesa didn't stop after halftime either, as senior Dong-Gi Shin's standout effort paid off in the 42nd minute. He took a bouncing ball from senior midfielder Jesus Estrada, headed it past a charging Tapia then calmly kicked it into the right corner.
Muir, the third-place team from the Pacific League, never quit.
"They didn't want to go down easily, and they fought back," Cordoba said. "We were just able to exploit their weaknesses. I was able to play Dong-Gi at mid and forward, and Jorge up front. We were able to play Estrada at the outside mid. We just moved things around, just seeing what we can do in the future. Even though it's the playoffs, I'm looking at what we can do for next year, trying to replace the missing pieces."
Senior goalie Peter Salas made seven saves for Mesa, which also relied on physical defense from sophomore Oscar Dorantes and junior Jovanny Dena. Salas said he was pleased after allowing just one goal nearly the whole game.
"Our defense has been solid all year," he said. "They communicate well with me."
Sanchez said Dorantes has been a leader since Mesa's last man on defense, Alexis Herrera, is just a freshman. Junior Jesus Delgado also led the defensive charge.
Salesian, yet another school with the Mustang as a mascot, will also be a tough test Friday. The Santa Fe League champions won CIF Southern Section Division V and Southern California Regional Division III titles last year.
"You want to make an impression?" Cordoba asked his team after Wednesday's victory. "Friday's when it starts."