The Harvard football team will be in a must-win situation tomorrow when it faces off against Princeton to determine whose Ivy season will stay alive and whose hopes will be dashed until next year.

On second-and-10 with 7:46 left in the first half of Brown’s 31-28 win over Princeton last week, Bears’ tailback Nick Hartigan broke loose—he broke through the Tiger line, broke away from the last defender in its secondary, and didn’t stop until he reached the Brown end zone.

That’s not all the three-weeks-running Ivy Offensive Player of the Week broke. Hartigan rushed for an epic 245 yards on 38 carries, breaking down the notion that Princeton could win games on defense or that defense could contain a star rusher.

“In the mud, Hartigan’s a tough back. There were times when it looked like he was down and he just sprang back into play,” Harvard coach Tim Murphy said.

At the start of the season, the spotlight was on the Tigers’ defense. For most of the season, it stayed there. Princeton has held opponents to an average of 18 points per game. At the core of its defensive unit has been its ability to stop the rush—the Tigers’ opponents have averaged 129 yards per game on the ground and only three touchdowns over the season.

But last Saturday, the defense-based team gave up 31 points and 451 yards of total offense.

“I’m not sure why they let up so many yards. That’s definitely not typical of their defense,” said Crimson tailback Clifton Dawson. “We expect a hard fight.”

This time it isn’t Hartigan—it’s Dawson. Harvard’s junior enters tomorrow’s game fresh off another 100-yard contest in which he broke the 3,000-yard career mark for the Crimson. The competition for best back in the Ivies is a Dawson-Hartigan race—likely bad news for the Princeton defense this weekend.

It isn’t only that the Tigers couldn’t stop Hartigan (to whom Harvard ceded 115 yards in a double-overtime thriller earlier this fall). Princeton’s vaunted secondary didn’t fare much better.

Brown quarterback Joe DiGiacamo completed 15-of-27 passes for 201 net yards—about average statistics for the signal caller, except that three of those 15 passes were for touchdowns.

On paper, the Tiger defense stands to put up a fight. When the Harvard offense takes its stance on the line of scrimmage, it’ll be stacked up against a few of the top defenders in the league.

“They’re a very physical, fast-flowing defense with a great corps of guys up front and in the secondary,” Dawson said. “We definitely expect a huge challenge.”

Senior cornerback Jay McCareins, the younger brother of New York Jets wide receiver Justin, leads the Ivies in interceptions with five. Two of his fellow defensive backs are among the top 10 pass defenders in the league, and the threesome has broken up a total of 17 passes.

“This is one of the better secondaries, probably the best secondary we’ll face this year,” Murphy said.

McCareins’ predilection for pick-offs could prove troubling to a Crimson pass game that has thrown 12 interceptions between sophomore quarterbacks Liam O’Hagan and apparent number-two Richard Irvin. In last week’s game against Lafayette, however, O’Hagan didn’t slip up, throwing for 207 yards and three touchdowns without an interception.

“We can’t just get out there and pound the football,” Murphy said. “We can’t be predictable.”

Linebackers Justin Stull and Nate Starrett are among the best at their position, or on defense as a whole, in the league. Stull has three sacks to his name this season.

But while Princeton may have given up 31 points, it still put 28 of its own on the board. With its defense underperforming, Princeton stayed in the game—and, for a while, led it, turning a 24-7 deficit into a 28-24 edge with three unanswered touchdowns. If Princeton’s defense didn’t come through, its offense compensated, although the statistics might not show it.

No Tiger rusher broke the 100-yard mark, although quarterback Jeff Terrell led with 88 yards and two touchdowns on the ground. With 173 yards and a touchdown passing, Terrell may be pose the greatest threat to the Crimson defense.

“It’s a very diverse offense, a very challenging offense. They spread the ball around the run and get the ball in the run game and the pass game to a lot of different people,” Murphy said.

Tigers running backs Rob Toresco and Greg Fields totaled only 105 yards combined.

Much depends on whether Dawson breaks through, whether the Tigers’ rushing and passing attacks can spread the Crimson defense too thin, and, of course, on whether both defenses hold up.

If they do, the game could prove a low-scoring slugout.

“We have a lot of confidence in their defense, a lot of confidence in our defense,” Murphy said.

—Staff writer Samuel C. Scott can be reached at sscott@fas.harvard.edu.