"Behind Enemy Lines" is a Thursday post on the Access Vikings blog. In advance of Sunday's Vikings-Lions game, Dan Wiederer of the Star Tribune interviewed Dave Birkett, the beat writer for the Detroit Free Press. Here are three things you need to know ...

1 The Lions are back in the playoff hunt.

When the Vikings left Ford Field on Sept. 30 with a 20-13 victory, Detroit had fallen to 1-3 and looked to be in danger of becoming an afterthought in the playoff race.

But the Lions have clawed back to .500 thanks to solid road victories over the Eagles and Jaguars plus an impressive rally to beat the Seahawks in Week 8.

Now, Birkett said, comes a critical three-game stretch that should make clear the direction the Lions are pointed by the time they lay down to rest Thanksgiving night. Following this week's game in the Twin Cities, the Lions return home to play Green Bay on Nov. 18 and then face Houston four days later.

"This three-game stretch here will ultimately decide whether they're playoff material or not," Birkett said. "They need at least two wins in this stretch."

2 Receiver Calvin Johnson is hurt and quarterback Matthew Stafford is hot.

Stafford and Johnson have yet to connect on a touchdown pass this season after hooking up for scores 16 times in 2011. Johnson's lone TD this season was a 3-yard grab from Shaun Hill.

So is the All-Pro receiver dealing with the infamous Madden curse, suddenly beat up as a result of being on the front cover of a video game?

"Calvin says he's a God-fearing man and doesn't believe in curses," Birkett said. "But he's definitely had more than his fair share of bumps and bruises this year."

Johnson has a sore knee after already dealing with injuries this season to a finger, foot and head.

Stafford is coming off two red-hot games in victories over Seattle and Jacksonville. The stats in those games: 56-for-82, 637 yards, three TDs, one interception.

"Stafford is the No. 1 reason to believe the Lions' turnaround is legit," Birkett said. "Early on, I think it just took him a little time to adjust to how defenses were playing him and taking away Calvin Johnson. But these last few weeks, he's been great on third downs. He's been more accurate and efficient. And the offensive line is playing well up front."

3 The Lions secondary remains vulnerable.

Detroit will do everything it can to stack the box against Adrian Peterson. But the Lions have yet to find stability in the secondary, having started a different defensive back combination in every game this season.

Safety Louis Delmas is in danger of missing his sixth game this season as he continues dealing with a nagging knee injury. Detroit's starters last week against the Jaguars were Chris Houston and Jacob Lacey at cornerback and Erik Coleman and Ricardo Silva at safety.

"Delmas is really the glue of the defense back there," Birkett said. "And they're noticeably weaker without him."