It's Super Bowl or bust for the Indianapolis Colts this season. After making it to the AFC title game last season, the Colts went all-out in the offseason in an effort to earn their way to Santa Clara in February. Indianapolis added running back Frank Gore and wide receiver Andre Johnson through free agency and drafted receiver Phillip Dorsett in the first round.

But while the offense should be better than ever, after four preseason games, it appears some of the issues from last season remain.

With regular season set to kick off Thursday, here are the five most important things we learned about the Colts during the preseason.

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1. The run defense may still be an issue

The Colts hoped a healthy Arthur Jones would help them accomplish their offseason goal of improving their run defense. But now Jones is out for the season after injuring his ankle Aug. 29 against the St. Louis Rams. Without Jones, stopping the run against a team like New England may once again prove to be a challenge. The run defense and the defensive line as a whole is a major area of concern entering the season.

2. The offensive line is a work in progress.

The Colts released veteran right tackle Gosder Cherilus and replaced him with second-year lineman Jack Mewhort, who played guard as a rookie. Mewhort struggled early, but settled in as the preseason progressed. Khaled Holmes was named the starting center, but he too is relatively inexperienced. Journeyman Lance Louis will start at left guard. Other than left tackle Anthony Castonzo, there's little about the line that inspires overwhelming confidence heading into the season.

3. The new guys love Andrew Luck

Pro Bowlers Andre Johnson and Frank Gore wanted to win a Super Bowl and both have said repeatedly one of the main factors that drew them both to Indianapolis was the presence of a young franchise quarterback in Luck. Gore even went as far as calling Luck "a football god." Gore and Johnson will be counted on the help Luck get the team to the Super Bowl, and so far, both appear to fitting in nicely.

4. Robert Mathis will be back shortly

Mathis, who is coming off a torn Achilles, was activated off the PUP list in late August and didn't appear in any of the Colts' preseason games. The linebacker has promised to be back in time for the season-opener against the Bills and the Colts aren't ruling it out, with head coach Chuck Pagano calling it a "possibility." Whenever the outside linebacker returns, the Colts will benefit from his leadership and productivity. Mathis had 19.5 sacks in 2013.

5. There's a lot on the line this season

Even with the contract extension wide receiver T.Y. Hilton signed during camp, the Colts have a number of key contributors entering the last year of their contracts. Left tackle Anthony Castonzo and tight ends Coby Fleener and Dwyane Allen will all be free agents at the end of the season, plus the team needs to prepare for the mega-extension Luck will surely command, perhaps as early as next offseason. Plus, head coach Chuck Pagano is in the final year of his contract as well, with his fate to be determined by how well the team performs this season.