The Nitros (3-8, 2-5 in league) got a standout defensive effort to hand the Tornadoes (6-7, 2-5) their second straight shutout.
Rosales, a junior forward, took advantage of Hoover's inability to clear the ball out of the goal box following a corner kick. She peeled away from the scrum before depositing a low shot past Hoover goalkeeper Christina Voskanian.
"It was pretty chaotic in there and I just went for it," Rosales said. "Everybody was all bunched up and the ball ricocheted to me. I just wanted to beat Hoover because they are our rival."
It marked the second consecutive match that the Tornadoes yielded a goal in the first minute. Hoover allowed an opening-minute goal in Wednesday's 4-0 league loss to visiting Burbank.
Glendale spent most of the match on Hoover's side of the field and limited Hoover to no quality scoring chances in the 80-minute match.
Hoover could muster just one shot on Glendale goalkeeper Natasha Wolhein.
"Our defense has been amazing of late," Glendale Coach Kristine Lowe said. "We didn't let down at all mentally and we kept on top of Hoover the whole time.
"It's Hoover that we are playing at home and you want to have the most enthusiasm that you can give."
Mizuki, an All-Area junior midfielder, capped the scoring in the 62nd minute.
She took a nifty pass from teammate Gabbi Chiriboga and whipped a left-foot shot past Voskanian.
Hoover first-year Coach Julie Testin said the Tornadoes showed improvement, but couldn't avoid another early letdown.
"That first goal killed us because it's hard to play with the mentality of playing from behind," Testin said. "When you have that mentality, it gets you out of the game.
"We tried to mix things up in the second half by changing our lineup. We had a good effort, but it wasn't enough."
Both teams are also suffering from injuries to key players.
Hoover, which competed without starting senior midfielder/forward Catrina Flores, lost the services of starting junior stopper Elena Torres early in the second half. She appeared to suffer an injury to her left leg.
Both are All-Pacific League selections.
Flores, All-Area selection, cracked her left wrist Wednesday and received medical treatment. Flores, who had her arm in a cast, said she will visit her doctor Monday to determine whether she'll be able to return to the field this season.
Glendale will be without sophomore midfielder/forward Samantha Santiestban until at least early February, Lowe said. Santiestban, who hasn't played since a Pacific League match against Burbank on Dec. 15, has been bothered by an ankle injury.
CHARLES RICH covers sports. He can be reached at (818) 637-3228 or by e-mail at firstname.lastname@example.org.