COSTA MESA — One of Corona del Mar High's goalkeepers played for another team on Tuesday.

Earlier in the day, Kat Hess was 29 miles away from the site where her high school girls' soccer team was going to play. Hess represented the U.S. under-17 women's national team in a match against Germany at the Home Depot Center.

Hess' high school team could've used her in a key Pacific Coast League match against Northwood at Jim Scott Stadium.

Without the standout freshman in goal, the Sea Kings gave up two goals, the most they have allowed all season in a match. That was more than enough for Northwood to win, 2-0, and hand CdM its first league setback.

It was a big loss as CdM, ranked No. 4 in the CIF Southern Section Division 1 poll, missed an opportunity to move into sole possession of first place in league. The Sea Kings went into the match tied with the Timberwolves atop the league with eight points each.

Northwood is now all alone at 5-2-0 in league and two points ahead of CdM. Coach Chris Woolley told his players that defending league champion CdM is now chasing them.

"It's a setback in winning league," said Middleton, whose team dropped to 3-1-2 in league. "I still think we can win league, though. We need to most likely win out the rest of our games and hope [University] and Northwood battle out and maybe tie."

What CdM does have over Northwood is one more league contest the rest of the way.

The Sea Kings have only played six matches, because their match against University last week was postponed due to rain. Middleton said the road match against University is set for Feb. 8.

Middleton said CdM will have Hess, who usually splits the keeper duties, available next week, when it closes out league play with three matches in four days.

"It's tough losing any player," said Middleton, when asked whether CdM missed Hess, who was called up to the U.S. under-17 women's national team on Jan. 20 for an eight-day training camp.

"We're still down two defenders [Brianna Westrup and Alexa Mamatas because of injuries]. When we have the strength of those two defenders back, it's tough to break us down to even get a shot on goal."

The Timberwolves took advantage of CdM's defense late in the first half and midway through the second half. The way they did it, against a defense that had only allowed nine goals in their first 17 matches, was impressive.

In the 33rd minute, Northwood created it best scoring chance since the opening minute. Kendall Mulvaney, playing the entire way because Hess wasn't around, got her gloves on the first threat, but not on the second one.

Northwood's Samantha Solaru won a bad clearance. The ball rattled around and she found it. From the left side, she dribbled in and cut inside, before turning to blast a shot toward the near post. Mulvaney drove to her right, unable to stop the ball.

The second time the Timberwolves found the back of the net, it came after they served the ball back in after a corner kick.

The ball skipped over the keeper's head. And there was Chinyere Chambers, who got around the keeper and tapped the ball in for a 2-0 lead.

The Sea Kings (11-3-4 overall) never answered.

Their attack was slowed down, or knocked down. It seemed every time CdM got near the box, midfielder Annie Alvarado went down after colliding with a defender. The referees let the teams play.

Alvarado crashed to the turf one last time.

She got tangled up with Emily Martinez. She stayed down, even after the whistle blew, signaling the end of the match.

david.carrillo@latimes.com

Twitter: @DCPenaloza