Both teams are 3-1 going into Week 5 but while the Bucs arrive in Chicago on the back of three straight wins, the Bears suffered the first defeat of the season last time out.

Here’s all you need to know ahead of Thursday Night Football.

After a slow start, there are signs the Tom Brady bandwagon in Tampa Bay is beginning to shift through the gears. Having looked rather rusty in the first three weeks of the season, the six-time Super Bowl champion rolled back the years in the 38-31 win against the Los Angeles Chargers, despite missing the injured Chris Godwin and Leonard Fournette and losing Mike Evans, LeSean McCoy and O.J. Howard for portions of the game.

Brady threw another pick-six—he has four interceptions threw the first four weeks of the season, compared with eight over the course of last season—but passed for 369 yards and five touchdowns and looked back to his best as the Bucs wiped out a 17-point deficit, marking the 28th time in regular season and playoffs combined the veteran quarterback has come back from a double-digit deficit to win a game—an NFL record.

With the win the Bucs improved to 3-1 for the season and remain top of the NFC South ahead of the New Orleans Saints and the Carolina Panthers, but the Bears defense could prove to be the toughest challenge Tampa Bay has faced so far.

The Bears defense ranks 9th in the league with just 5.2 yards allowed per play—along with the Broncos, the joint-best of any team the Bucs have faced so far—11th against the pass—the second-best of teams Tampa Bay have played so far after Carolina—and eighth in terms of total points allowed, making it the stingiest of any defensive units the Bucs have come across so far.

The Bucs also have to deal with a mounting injury toll. Howard is out for the season with an Achilles injury, while Fournette and McCoy did not practice on Tuesday, along with Evans and fellow were wide receivers Chris Godwin, Justin Watson and Scotty Miller —which could make life harder for Brady, who has passed for 974 yards at an average of 324.7 per game, eight touchdowns and two interceptions for a 103.0 passer rating in three career starts in Chicago.

The Bears, meanwhile, have far fewer certainties at quarterback. Chicago benched Mitchell Trubisky, who had won the first two games of the season, halfway through Week 3’s game against the Atlanta Falcons, handing the keys to the offense to Nick Foles. Trubisky’s future had been in jeopardy dating all the way back to last season and Foles sparked a momentous comeback against Atlanta, leading Chicago to erase a 16-point deficit and a third consecutive win.

The MVP of Super Bowl LII, however, looked far more subdued in his first start for the Bears on Sunday, as Chicago lost 19-11 against the Indianapolis Colts. While the Bears defense remains among the best in the league, Chicago has failed to get things going on the offensive side of the ball scoring fewer than 20 points in 11 of its last 20 games.