The junior midfielder was part of a 5-0 run with one goal and two assists to open the game's scoring and was instrumental throughout, finishing with three goals and two assists, in the Marauders' 11-7 win.
"We came out really hot because we were excited," Harney said. "We have the No. 1 spot on the line. We're taking every game seriously."
Katie Kirk, who won five of 11 faceoffs for Bay Shore (11-1), scored off an assist from Carly Cox to cap the run with 13:43 left to play in the first half.
After Harney scored unassisted with 1:10 remaining, it was 7-1 Bay Shore at halftime.
"It was the game plan," said Bay Shore coach Allison Pfeffer, referencing the Marauders' placing an emphasis on getting off to a good start. "Our girls are so talented and capable."
Cynthia Del Core is certainly one of them. The senior midfielder seemed to have an answer for East Islip (8-4) in the second half, netting an unassisted goal at the 13th minute to make it 9-4.
"Whenever we make a mistake, we make everyone respond in a different way," said Del Core, who had three goals.
Redmen senior midfielder Elizabeth Vetter helped East Islip stay in the game, scoring off a restart with 11:29 left in the second half, to cut the Marauders' lead to four, before freshman defender Alexa Mattera made it 9-6 less than a minute later.
"We were winning more draws and getting more aggressive on ground balls," said Vetter, who led the Redman with three goals. "We were careful with the ball, keeping our heads up and looking for the other person."
When Amanda Voges scored her second goal in transition off an assist from Erin Ilchuk, it made it 10-6 in favor of Bay Shore with nine minutes left to play. Like her teammates, Voges credited the Marauders' ability to answer the call and be resilient when the time presents itself.
"We always try to answer," Harney said. "It's about accountability. Everyone is a threat on our team."
East Islip coach Steve Levy knows it all too well. "They have so many kids who can make plays," said Levy, who saw Lee-Ann Salim make a game-high eight saves, which enabled the Redmen to get back in it. "I think we were tougher in the second half, smarter. We got after the ground balls and took advantage of our opportunities on offense."