After their wild season opening victory over Syracuse, it looked like Northwestern fans would have to endure another season of the "Cardiac Cats".

Ever since September 1st the Wildcats defense has improved tremendously. In the three games since the opener, Northwestern has only allowed a combined 33 points compared to the 41 they allowed in Week 1.

They've also only allowed opposing teams to gain an average of 270 yards per game in that stretch.

What's even more impressive is some of the teams they've defeated along the way. Despite having to make a comeback at the 11th hour, the Syracuse victory was still huge for both the Wildcats and the Big Ten Conference.

In Week 2, Northwestern successfully defended their home turf in a 23-13 victory over Vanderbilt. Even though Vandy's football program has been a door mat since guys like Jay Cutler and Earl Bennett moved on to the NFL, it's not often that a Big Ten team defeats an SEC team.

The victory over the Commodores isn't just a win for Northwestern, it's also a win for the Big Ten who has struggled against the Southeast Conference in recent years.

Northwestern has actually won two in-a-row over Vanderbilt, the Wildcats defeated Vandy on their home field in the 2010 season opener.

The next team to fall to Pat Fitzgerald's squad were the Eagles from Boston College. The Eagles came into the game averaging 30 points and 400 offensive yards per game.

The Cats' soundly defeated the Eagles 22-13 and the defense held BC's powerful offense to under 400 yards. Northwestern was the first team to keep BC's offense from reaching their season averages.

This past week, the Wildcats took on the lower division South Dakota Coyotes. It wasn't a surprise that they defeated SDU, but the final score of 38-7 may have surprised some.

Thanks to this re-energized defense, the Wildcats are now just to wins away from bowl eligibility. What's more important, the Cats' are one of only three unbeaten teams left in the Big Ten.

The other teams are Ohio State and Minnesota. Northwestern does not play OSU this year, but they will meet division rival Minnesota on October 13th. 

If the Wildcats can keep up this aggressive mentality on defense they will continue to have success down the line.

Of course the best course of action for them will be to take things one game at a time. This weekend the Wildcats complete the fourth game of this homestand when they play host to Indiana.

The Hoosiers seemed to be an improved team this year. They are 2-1, they're coming off a bye week, and their offense averages 30 points and 500 yards per game.

This is not the same Hoosiers team that has been in the gutter in years past. This week they will come to play and they will look to ruin NU's undefeated campaign.

This will be another big test for Pat Fitzgerald's defense, the question is can Northwestern rise to the challenge again?