Will 'FitzMagic' shine against tough Bears defense?

In the NFL, it's dangerous to assume you have any team figured out before the fourth or fifth week of the schedule, which makes these next two weeks a couple of the most interesting of the season.

Virtually no one projected either the Tampa Bay Buccaneers or the Bears to be first-place clubs heading into their Week 4 matchup Sunday at Soldier Field.

Now we get to learn a lot more about just how good they really are.

You've probably heard the Bucs' story by now. Quarterback Jameis Winston gets suspended for the first three games of the season, and expectations hit rock bottom with 14-year journeyman Ryan Fitzpatrick making his seventh NFL stop coming off the bench to try to keep them competitive.

But out of nowhere Fitzpatrick turns into "FitzMagic," averages 410 yards passing and 3.7 touchdown tosses a game, and the Bucs are a field goal loss at Pittsburgh away from being 3-0 with the NFL's No. 1 offense and passing game while ranking fourth in points scored.

His partners in crime, receivers Mike Evans, DeSean Jackson and Chris Godwin, have 3 TDs apiece and are averaging 16, 26 and 13.2 yards a catch, respectively, while auditioning for this year's Pro Bowl, and tight ends O.J. Howard and Cameron Brate have been matchup nightmares when on the field together.

Expect Bears undrafted rookie free agent Kevin Toliver in his first NFL start to have a bull's-eye on him all day long.

But peek behind the curtain and you find a few cracks in the Bucs offense's foundation.

Tampa's Week 1 and Week 3 opponents, New Orleans and Pittsburgh, have been two of the worst defenses in the league to date, ranking 30th and 32nd and 29th and 28th, respectively, in total defense and points allowed.

There also are the issues of Tampa's nonexistent ground game, 30th in the league, their 24th and eighth rankings in interceptions and sacks allowed and the fact the Bears' defense will come in ranked fifth overall, third in interception percentage and first in quarterback sack percentage.

You cannot discount the explosiveness of either the Bucs' offense or the Bears' pressure defense.

It seems almost certain the Bucs' unremarkable offensive line of Donovan Smith, Ali Marpet, Ryan Jensen, Caleb Benenoch and Demar Dotson will dictate the success of the offense against the Bears depending on how well it can stand up to the Bears' front seven.

If the strength-vs.-strength matchup turns out to be a draw, we'll turn to see how the Bears' anemic offense fairs against the Bucs' porous 'D.'

As good as the Bucs have been with the ball, they haven't offered much resistance on defense.

The Bucs are 31st in total defense, 31st against the pass, 29th in interception percentage, 25th in quarterback sack percentage and 29th in points allowed.

The only thing they've done well is defend the run, where they are third in run defense and seventh in average yards a carry.

Normally, you'd think those numbers are because everyone is throwing on them and hasn't had to run, but four of the Bucs' front seven are Pro Bowl-caliber defenders in Gerald McCoy, a perennial Pro Bowler at the three-technique, and Jason Pierre-Paul, LaVonte David and Kwon Alexander.

Identify and slow those four and the Bucs are in trouble.

Tampa's best cornerback, Vernon Hargreaves, is on injured reserve, leaving the aging Brent Grimes and Carlton Davis at cornerback, and Davis will be battling a balky groin if he can go at all Sunday.

Safety isn't much better, where former Bear Chris Conte ended up on IR last week. His backup, Jordan Whitehead, will try to step in with a nagging hamstring, and Justin Evans is just a guy next to him.

Tampa should be tailor made for a Mitch Trubisky coming-out party, but if the Bears' offense continues to stutter, the defense may not be able to win this one on its own.

This will not be a game in which either team wants to play from behind, so the first score or two could be the most important.

• Hub Arkush is executive editor of Pro Football Weekly. Write to him at harkush@profootballweekly.com, and follow him on Twitter @Hub_Arkush.