After one half, the No. 19 Harvard men’s lacrosse team looked primed to pull of its biggest win of the season. In the second half, the Crimson would have been hard-pressed to beat anyone.

Leading 4-2 over No. 10 Cornell at halftime, Harvard was outscored 9-0 after intermission, as the Big Red rolled to an 11-4 victory Saturday at Jordan Field.

Freshman sensation Sean Greenhalgh sparked the Big Red (7-1, 3-0 Ivy) with four second-half goals, giving him 21 on the season. Meanwhile Cornell’s top-ranked scoring defense stifled the Harvard attack in the second half, holding the Crimson to just three shots on goal and forcing multiple turnovers.

“They adjusted to what we were doing on offense,” co-captain Michael Baly said. “Part of that is our fault. We were telegraphing our passes and they did a good job taking advantage.”

Going into halftime, Harvard (4-3, 0-2) looked to be in prime position to pull off the upset. The Crimson controlled the last five minutes of the second period, scoring two goals against a confused Big Red defense.

Junior attacker Jay Wich took a pass from freshman Mike McBride and fired a shot past Big Red goaltender Justin Cynar to give Harvard a 3-2 lead with 5:05 remaining in the half. Co-captain Jim Christian bounced a shot into the Cornell net with just 43 seconds remaining to give Harvard the 4-2 advantage.

“On every single ground ball and every single broken play, we were going after the ball harder than they were,” Baly said.

But the Crimson could not carry that momentum through intermission. Cornell controlled play from the opening faceoff in the second half, pulling within one when Greenhalgh scored his first goal with 12:16 remaining in the third, converting at point-blank range.

“They started off real hot in the beginning of the second half, and it put us on our heels,” McBride said.

The Big Red tied the game at 4-4 less than a minute later, and took the lead for good with 7:52 left to play on another Greenhalgh score. Justin Redd scored with 6:09 left to give Cornell a 6-4 lead.

Harvard settle down a bit after that, holding the Big Red scoreless for the next nine minutes.

Yet while the Crimson held Cornell at bay, it could not generate any offensive pressure, and the Crimson defense finally broke down halfway through the final period.

“Defensively we played a solid game,” McBride said. “But it’s really hard to play defense well for that long in the game. They just controlled all the play.”

Greenhalgh opened the floodgates with his third goal at the 11:51 mark of the fourth period. Less than three minutes later, Cornell had scored two more times, taking a 9-4 lead and effectively putting the game out of reach.

The statistics tell the story of Harvard’s second-half struggles. After winning a majority of the faceoffs in the first half, the Crimson lost eight of 10 faceoffs after intermission. The team was outshot 21-9 and grabbed just seven of 21 possible ground balls.