Napier, who earned a nomination for McDonald's All-American this season, led all scorers, pouring in 34 points — including 14 in the first quarter.
Napier, who has been the team's leading scorer all season, said she feels no pressure to carry the Guards (23-7).
"I just want to play hard for my team," said Napier, who along with Smith and Averie Guzman helped Bell-Jeff win state and Southern Section titles as freshmen. "My teammates are so amazing to me. They pick me up when I'm down, they encourage me, so I feel no pressure. I just want to come out and play my heart out for these girls."
Bell-Jeff, which won its fifth straight Santa Cruz League championship this year, moves on to the semifinals against the winner of the quarterfinal between No. 7 Gardena Serra and No. 2 Oaks Christian. The game will be Saturday at 7 p.m. and the Guards will be on the road.
"We know we are going to be on the road for the next round, and we know we're going to go up against very good competition, whichever team wins," Bell-Jeff Coach Jaclyn Johnson said. "But we have seen both teams and we'll know what to expect from them."
The Guards caught a break early in the fourth quarter against Chaminade (23-5), the two-time Mission League champion. With 7:40 left and Bell-Jeff holding a seven-point lead, the Eagles' leading scorer, senior Annie Tarakchian, knocked Napier down with an errant elbow, drawing her fifth foul. She left the game after scoring 16 points and grabbing 15 rebounds.
Another Chaminade starter, junior Robyn Brown, fouled out with 1:09 left in the game.
Johnson said her team came out well-prepared for the Eagles.