PRINCETON, N.J.—Just over 15 minutes into its game at Princeton Saturday, the Harvard football team was doing exactly what it had done in each of its Ancient Eight matchups over the past 700 days—simply dominating.

Senior quarterback Colton Chapple had just thrown his third touchdown of the contest to put Harvard up, 20-0. The Crimson offensive machine looked flawless, just as it had through its first five contests, when it scored more points than any Harvard team through that point since 1892. The Crimson was well on its way to its Division I-leading 15th straight win, and a game that was supposed to be well-contested simply wasn’t.

But senior kicker David Mothander’s ensuing extra point attempt was blocked, setting in motion a series of Crimson (5-1, 2-1 Ivy) miscues that would help result in Princeton (4-2, 3-0) pulling off a stunning 39-34 comeback victory that gives it control of the Ivy title race with four weeks to go.

“We just made too many mistakes,” Crimson coach Tim Murphy said. “You can see them on offense, you can see them on defense, and you can see them on special teams.”

One such blunder came on Harvard’s next possession when following a 19-yard rush to the Princeton 25, senior running back Treavor Scales was stripped by the Tigers' Phillip Bhaya and fumbled for the first time all season as the Tigers recovered along the sideline.

But after a Princeton punt, Chapple led a 77-yard drive and had the Crimson set up once more to go ahead, 27-0, with a first-and-goal from the two. The senior ran it in himself on the ensuing play to do just that, but classmate John Collins was called for a holding penalty, pushing Harvard back 10 yards. On third down, Chapple threw up a lob towards a double-covered Cameron Brate that was intercepted by Princeton's Mande Sheaffer, and what had been six points had turned into zero.

Following a Tigers three-and-out, Chapple went right back to work with 1:18 to go in the half. But a 27-yard strike down to the Princeton three to junior Andrew Berg down was wiped out on an offensive pass interference call that pushed Harvard out of field goal range and cost the team another great chance to score before the break. For the third consecutive possession, the Crimson had failed to score on a drive in which it had the ball inside the Tigers 30.

None of that seemed like it would matter as the two teams headed to the locker rooms. In the first half, the Crimson had outgained Princeton—which entered the game with the second-ranked defense in the FCS—415 yards to 51, had 21 first downs to the Tigers’ four, and most importantly, still held a 20-point lead.

But ever so slowly, the momentum started to swing towards the home team as the Crimson continued to make mistake after mistake.

After the Tigers opened the second half with an 86-yard touchdown drive, freshman Paul Stanton dropped the ball on the ensuing kickoff. Instead of diving on it to secure possession, Stanton tried to pick it up and run, but the rookie was unable to get a good grasp on the pigskin. Jakobi Johnson recovered at the Tigers four, leading to a Princeton field goal.

Chapple responded by leading back-to-back scoring drives, as touchdown passes to Juszczyk and Brate put Harvard up, 34-10. Things had stabilized once more, and with 13 minutes to go in the game, the Crimson looked well on its way to an impressive win.

Princeton’s Connor Michelsen led the Tigers down to the Harvard seven on their ensuing drive but threw a poor pass on first-and-goal that went right through the hands of senior linebacker Alexander Norman, who likely would have been able to return an interception to the house.

Instead, the Tigers took advantage of Norman’s drop by scoring on the next play and adding a two-point conversion to cut the Crimson lead to 34-18.

On the next Harvard series, senior Jacob Dombrowski’s punt was blocked, and within five plays, the Tigers had scored eight more to cut the deficit to a single possession.

Chapple brought Harvard back down to the Princeton five, putting his team on the doorstep of a game-clinching score. But three successive running plays went nowhere, and after blocking an extra point and a punt, the Tigers this time got their hands on a 22-yard Mothander field goal attempt to keep the Crimson off the board.

Up two with time winding down on its next drive, Harvard came up one yard short of what would have been its 34th first down on Juszczyk's 15th reception—second-best in team history—and was forced to give the ball back to the Tigers.

It was on Princeton's final drive on which the most costly Harvard miscues came.

The Tigers had a first down at their own 37 when backup quarterback Quinn Epperly—who had replaced an injured Michelsen—was sacked, ticking precious seconds off the clock. But senior John Lyon was called for an excessive celebration penalty, turning a 2nd-and-17 at the Princeton 30 into a 1st-and-10 at the Tigers 45.

Two plays later, Epperly made a poor read, throwing the ball directly at junior safety Chris Splinter. But the safety could not hold on to what would have been a game-ending interception for the second time in the contest, and after failing to put the game away again, the Crimson soon learned that Splinter’s drop would be the straw that finally broke the camel’s back.

Within seconds, Epperly had found Roman Wilson on a 39-yard fade to the back corner of the end zone, giving Princeton its fourth touchdown in 11 minutes and its 29th unanswered point to clinch the upset and leave the Crimson stunned.

The Tigers had won a match in which it had given up 634 yards of offense, thanks in large part to three Crimson turnovers and 12 Harvard penalties, compared to just five for Princeton.

Harvard, meanwhile, had lost a contest in which its quarterback broke the all-time Crimson passing record with 448 yards and tied the all-time record with five touchdowns, in which Scales eclipsed 100 yards on the ground, and in which Jusczcyk, Brate, and Berg all registered over 100 through the air.

The contest followed a similar script to last year’s game between the two teams, when Harvard went up 26 before a dramatic Tigers second-half rally cut the Crimson lead to 42-39. But last season, Harvard answered back with two touchdowns to put the game away and keep its undefeated league season rolling. This year, a much-improved Princeton squad was able to finish the comeback and take first place for itself.

“[Harvard is] probably the better team,” Princeton coach Bob Surace said. “But we got some breaks, and we’re very fortunate.... I’m glad we didn’t play them in a seven-game series, but it’s every given Sunday—or Saturday.”

—Staff writer Scott A. Sherman can be reached at ssherman13@college.harvard.edu.