Junior Ruben Orozco and sophomore Terry Unruh both threw hitless innings while striking out two, and freshman Nik Klungreseter, as well as seniors Tucker Woods and J.R. Bromberg added scoreless innings as the Lions maintained the shutout through eight innings.
Junior closer Kevin Ponzo, operating well outside a save situation due to an 8-0 lead, allowed one unearned run in the ninth, when a hitter that reached on an infield error, later scored.
Vanguard Coach Ralph Grajeda said his plan was to get some mound work in for his hurlers, since it had been a week since the Lions last played a game.
The Lions also lashed 10 hits to improve to 17-15 and extend their winning streak to three against the Riverside-based school that fell to 3-26-1.
La Sierra, in fact, had just 11 available players for Tuesday's game, and its starting pitcher, senior Kenneth Curiel, also batted cleanup.
Still, Curiel, who fell to 2-9, nor two La Sierra relievers were overmatched by the Vanguard offense, which managed multiple hits in only three innings and scored two runs in the third and seventh innings.
Junior shortstop David Kiriakos was two for four with one run batted in, while junior third baseman Bryce Arroyo had three RBIs while managing only one hit.
Senior outfielder Brandon Young drove in two runs, while seldom-used senior Kyle Willett produced the hosts' lone extra-base hit with a pinch-double in the eighth. Willett is two for eight this season.
The Lions added potency by stealing a combined seven bases (two by Young), but were just three for 12 with runners in scoring position.
"It was very academic today," Grajeda said. "It was about our guys getting their jobs done and getting their work in."