And now the real test begins.

Last year, Yale and Penn — the Ivy League’s two toughest defenses — faced off in what, sure enough, was a defensive struggle. The Bulldogs were held to 15 rushing yards, while the Quakers never reached the endzone. Regardless, Penn staged a narrow comeback, kicking three consecutive field goals to secure the 9-7 victory.

A similar game might be in store tomorrow afternoon at Penn (3-2, 2-0 Ivy), as the Bulldogs (3-2, 1-1 Ivy) face one of their toughest opponents on the schedule and try to add to their two-game winning streak.

This year, Yale and Penn once again enter their game with the conference’s two strongest defenses. The Bulldogs are first in scoring defense (12.4 points per game) and second to Penn in total defense — 248 yards per game, compared to 227 for the Quakers.

“They’re a hard-nosed football team,” head coach Tom Williams said. “I’m excited about matching the intensity and toughness that they will bring to the game. We pride ourselves as being a smash-mouth, tough defense, so we’re going to try to fight fire with fire.”

But Yale received a blow to its defense this week after medical tests showed that strong safety and leading tackler Larry Abare ’10 fractured his arm last week against Lehigh. He is out indefinitely and his career as a Bulldog could be over, although he hopes to be healthy for The Game against Harvard.

From here on out, every team the Elis face will be an Ivy League team, and after having already lost to Cornell, the Bulldogs are going to have to pull off an impressive run if they are to challenge for the conference title.

“[H-back] John Sheffield [’10] and I were talking and he said, point blank, ‘everything is for keeps now,’” tight end A.J. Haase ’10 said. “That’s the truth. Every game means everything to us now, so it’s definitely like a new season.”

With Abare out and Penn having a stronger offense than Lehigh did in their 7-0 loss to the Bulldogs last week, Yale is going to have to recapture its offensive form.

Last week quarterback Brook Hart ’11 was held to 86 yards and threw zero touchdowns and three interceptions.

In fact, the only Yale points came from captain and linebacker Paul Rice’s 40-yard touchdown run off of a fake punt play.

“It wasn’t the prettiest game I’ve ever been a part of, but we’re not going to apologize to anybody about how we win a football game,” Williams said. “There are a lot of good lessons to learn, and it’s certainly better to learn those after a win than after a loss.”

The offensive line will also have to step up. The Quakers lead the Ivy League with 15 sacks, while the Bulldogs have allowed a league-worst 16. The offensive line has shown improvement recently, though, having allowed a combined total of three sacks in the past two games.

“If we do our jobs things are going to click,” Haase said. “Pretty much all we have to do is execute.”

Penn is currently on a three-game winning streak after having forced seven turnovers in their 27-13 victory at Columbia last Saturday.

The Quakers will likely try to rely on their rushing game, which averages 138 yards a game, second in the Ivy League. Freshman tailback Lyle Marsh is averaging 4.5 yards a touch, and ran for 120 yards against Dartmouth.

Like Yale, Penn has lost to Lafayette. The Quakers’ 20-17 loss, however, came in overtime, whereas the Bulldogs were trounced by the Leopards 31-14.

Wide receiver and kick/punt returner Gio Christodoulou ’11, who has missed the past three games with turf toe, announced that he will be sitting out the rest of the season. Since he played in just two games this season, the decision allows him to retain two more years of eligibility.

He has so far been duly replaced by Chris Smith ’13, who is third in the Ivy League in punt return yardage and has made 13 catches for 174 yards.

With Harvard and Penn still undefeated in Ivy League play, a win against the Quakers would be important for the Elis in terms of remaining in the title hunt.

“We are in charge of our own destiny,” Williams said.

Kickoff is officially scheduled for 3:36 p.m. and can be heard on WELI (AM-960, and WYBC (AM-1340,