AMBRIDGE — For the third consecutive season, Mars' orbit will cross Highmark Stadium.

Behind a suffocating defensive showing Tuesday night at Ambridge's Moe Rubenstein Stadium, the Planets downed Montour, 1-0, in the WPIAL Class 3A girls soccer semifinals.

“There's a lot of familiarity,” Mars coach Blair Gerlach said. “They're in our section. We see them twice a year. We knew that they would have players sitting (back) and that they would try to counter.”

Mars had claimed both teams' prior meetings this fall in shutout fashion. Each team came in having won their first two playoff matchups by a combined 13-0 score.

Neither side could get much of anything going early. Mars' Maddie Wolf's harmless crosser on a corner kick in the 2nd minute was either team's only real scoring chance until, in the 17th minute, Piper Coffield wove through the defense down low and hooked a shot at the left of the net for Montour goalie Ashley Vith to pull in.

Almost a minute later, the Planets' Leana Cuzzocrea lofted the ball for 25 yards out. This time, Vith dropped to her knees, misjudging its bounce and allowing it to float through her raised arms and into the twine.

“They just had so many players in the box that it can be frustrating at times,” Gerlach said. “But, at the same time, with them sitting so deep, our goal came from outside the 18. It kind of worked in our favor once, and that was all that was needed.”

Being down a goal to Mars hasn't boded well for opponents.

“I think, when you score that first goal, it's a sigh of relief,” Gerlach said. “You go, 'We got a mistake to make and still not be in a (bad) position.”

Not long after, Montour's Saveria Ulizzi fired the Lady Spartans' first shot, straight into the arms of Mars goalie Megan Boddy.

In the half's last three minutes, Montour retained possession in Planets' territory. Eliana Davin's crosser was gobbled up by Boddy in the 37th minute. Her effort in the next minute was shielded by Gwen Howell.

Mars dictated possession for most of the second frame, with Addison Girdwood, Aly Cooper, and Howell getting off shots. The second of Girdwood's tries came in the 55th minute, her point-blank boot being batted away by a diving Vith.

Back-to-back corner kicks by Wolf in the 56th minute were also disposed of by the Lady Spartans' defense.

Montour's Grace Bannon would notch a shot in the 67th minute. Natalie Alan would hurry a corner kick with nearly 30 seconds to go in a last gasp to even the score, but it was headed safely out of a crowd, sealing the Planets' victory.

The shutout was the fifth in as many straight outings for Mars.

The Planets play Plum — a 2-0 winner over South Fayette — at 1:15 p.m., Satrurday in the championship ganme at Highmark Stadium.