Two years ago in South Bend, Stanford and Notre Dame matched up in a defensive struggle that ended with the Irish making a goal-line stand in overtime in which they stopped Stepfan Taylor on four consecutive attempts from inside the 4-yard line.

We might see a similar a game Saturday. Stanford and Notre Dame are two of the three FBS teams that have not allowed more than 17 points in a game this season. The other is Ole Miss.

Although both teams rank in the top five of the FBS in scoring defense, they used different methods to get their results. Stanford has conceded almost nothing this season, whereas Notre Dame has taken more of a bend-but-don-t-break approach.

Stanford

Despite losing several starters from last season, including Trent Murphy, Shayne Skov, Josh Mauro and Ben Gardner, Stanford might be better on defense. The Cardinal are allowing the fewest points per game (6.5) in the FBS, including shutouts against their two non-Pac-12 opponents.

They have allowed 0.39 points per drive, second-fewest in the FBS behind TCU (0.31). For some perspective, the fewest points per drive allowed by a defense in the previous 10 seasons was 0.54 by Alabama in 2011.

How good has Stanford’s defense been? Well consider these stats:

• The Cardinal are the only FBS defense allowing less than 200 yards per game and are on pace to allow the fewest passing yards per game (74.0) of any team in the last 15 seasons.

Stanford Defense - 2014

• Opponents have failed to gain a first down or score a touchdown on 55 percent of their drives against Stanford this season. Only TCU (60 percent) and Louisville (59 percent) have been better.

• Stanford has allowed the fewest plays (5) and completions (2) of 20 yards or more in the FBS this season.

• Stanford has allowed a Power Five-low 36 yards after the catch per game and has allowed three receptions of 10 or more yards after the catch, which is three fewer than any other Power Five defense.

Notre Dame

Notre Dame also appears to have reloaded on defense after some key departures. The Irish lost Stephon Tuitt, Louis Nix III, Prince Shembo and Bennett Jackson to the NFL Draft and their coordinator, Bob Diaco, to UConn as head coach. Yet, they are allowing 11.5 points per game, fourth fewest in the FBS and became the first team since 1984 to shut out Michigan.

The Irish have bent this season, but rarely broke. They rank 49th in the FBS in yards per play (5.2), but sixth in points per drive (0.8). Opponents have scored on 20 percent of their drives after gaining an initial first down against the Irish, fourth best in the nation and 23 percentage points lower than the FBS average.

What has made the Irish successful?

Forcing turnovers

The Irish have forced 2.5 turnovers per game this season, tied for 16th most in the FBS.

Getting off the field on third down

Notre Dame is holding opponents to a 33 percent third-down conversion rate, down from 42 percent last year.

No penalties

Notre Dame has committed five defensive penalties this season, tied for 10th fewest in the FBS. Of those five penalties, three resulted in a first down, which is seventh-fewest.