Senior linebacker Connor Sheehan put Harvard on the board first with a pick six. Sheehan returned two interceptions for scores, his first career defensive touchdowns.

Columbia quarterback Trevor McDonagh may have nightmares tonight of Harvard linebackers.

Coming into Saturday’s matchup with the Lions (0-8, 0-5 Ivy), Harvard (8-0, 5-0) had yet to score a defensive touchdown on the season. With nine minutes left in the third quarter, the Crimson had three pick-sixes—all off McDonagh—and might have had a fourth defensive touchdown had sophomore linebacker Eric Ryan not fallen just shy of the end zone after picking up a fumble.

“I’ve been doing this a long time and I’ve never been in a game like that, 28 points directly off turnovers without any transition in between,” Columbia coach Pete Mangurian said. “Obviously it changes the whole complexion of the game…. We just didn’t execute and they ran it back in for scores and that changes everything.”

Even without starting quarterback Conner Hempel, the Crimson, powered by a dominant defense, handily defeated the Lions at home, 45-0, to remain atop the Ivy League. Harvard, which handed the Lions their first shutout of the year, has now held Columbia scoreless for the last three years.

While the offense struggled to mesh early on, the defense took charge. Crimson senior defensive end Zack Hodges, who leads the program in career sacks, went down on the first play of the game and sat out most of the first quarter. But Harvard’s defense didn’t need Hodges.

On Columbia’s second drive, McDonagh targeted receiver Ryan Flannery. But junior linebacker Eric Medes collided with Flannery, popping the ball up, and senior linebacker Connor Sheehan was right there to catch it and take it 48 yards back for Harvard’s first touchdown of the day.

McDonagh’s bad luck with Harvard’s linebackers didn’t end there—two possessions later, junior linebacker Matt Koran picked off the signal caller and ran it back 34 yards for McDonagh’s second pick-six of the day, putting Harvard up by 14.

Then, on the Lions’ opening drive of the second half, McDonagh’s pass again ended up in Sheehan’s hands, and the senior ended up in the end zone for the second time that afternoon. Sheehan’s 49-yard return gave Harvard a 42-point lead.

Following the interception, Mangurian pulled McDonagh in favor of freshman quarterback Anders Hill. The Lions came closest to scoring on Hill’s first drive of the game—Hill moved the squad down inside the Harvard 10-yard line, but junior defensive back Asante Gibson broke up a pass on the goal line to keep the shutout streak alive.

With a fumble recovery by Ryan in the second quarter, another by senior defensive back Ryan Jones, and a pick on Hill by rookie defensive back Tim Haehl, the defensive unit recorded six takeaways on the day, its highest total of the season. Jones also blocked a punt, but the Crimson couldn’t convert the opportunity into points when kicker Andrew Flesher’s 24-yard field goal attempt hooked wide left.

“We’re playing great team defense,” Harvard coach Tim Murphy said. “We rarely make mistakes, which is the most important thing. We play extremely hard. It’s a very, very close unit, a very close team. Because of that it’s really been a special team defensively. Clearly we’ve got a lot of football left to play, but clearly our identity, if you have to choose one identity as a team, is we’re a great defensive team right now.”

Columbia won the time of possession battle by nearly 15 minutes but had almost 200 yards fewer of total offense and punted the ball eight times on the day.

Hempel hurt his shoulder last weekend against Dartmouth and was not dressed Saturday, leaving junior Scott Hosch to start under center. Hosch and company were unable to get into a rhythm through the majority of the opening two quarters and could not put together a scoring drive until one minute remained in the half, when it took the Crimson just two plays to find the end zone.

Junior running back Paul Stanton broke free for a 37-yard dash, and Hosch threw a bullet to senior wideout Seitu Smith to extend the lead to 28.

Harvard’s offense came out strong after halftime, scoring on its first two possessions. Sophomore quarterback Joseph Viviano III got his first significant minutes of the season when Murphy elected to replace Hosch with Viviano after Harvard increased its lead to 35. Viviano drove the team all the way down to the Columbia four-yard line and demonstrated his mobility with a 53-yard scramble, but the quarterback coughed up the ball inside the Lions’ five to lose possession.

With senior running back Andrew Casten out with injury as well, freshman running back Semar Smith shouldered carries alongside Stanton. Smith recorded 112 rushing yards as well as his first collegiate touchdown.

Early in the second half, Columbia attempted a lateral pass deep in its own territory, but the errant toss fell to the ground, and Ryan was there to scoop it up and take it to the Lions’ one-yard line. One play later, Stanton punched it in to give the home team a three-score lead.

—Staff writer Samantha Lin can be reached at samantha.lin@thecrimson.com.