The tricks are endless. Cornerbacks grab and hold, nudge and pull. The rules are bent. They drape like blankets, shadowing from shoulder pads to cleats. The coverage is perfect. The football is in midair.
And Calvin Johnson catches it anyway.
Here is the challenge of covering the NFL's best wide receiver. It's not the imposing, 6-foot-5 frame. It's not the versatility of playing in the slot or perimeter. It's not even the fact nobody before him — and, quite possibly, nobody after — has had a 4.3-second, 40-yard speed while weighing 240 pounds.
The challenge of stopping Megatron is this: all the elements can be in their right place, the coverage picture perfect, and it might not matter.
"Just line up next play and attack him again. Really, that's all you can do," Green Bay Packers cornerback Davon House said. "Because he's gonna get his catches and his yards. I don't think anyone has literally, totally shut him down since he's been in the league for eight years. So, really, contain him and make your plays when the ball comes your way."
Solving the problem Detroit Lions receiver Calvin Johnson presents is impossible math. More than one solution provides the same, wrong answer.
Teams can turn to man coverage. They can go zone. Each secondary mixes and matches, rarely giving the same look twice in a row, making every effort to keep Johnson on his heels.
The same routine has been followed for eight years. Throughout his career, Johnson has seen everything a defense can throw at him. He's beaten them all.
Packers cornerbacks coach Joe Whitt Jr. can't find a worthy comparison. Randy Moss was long and fast, but not 240 pounds of muscle. Terrell Owens was tough after the catch, but he didn't stand 6-foot-5. Trickle down the list of modern NFL greats, and there's nobody who possessed this kind of skill set.
"There's not a corner in this league — not one — that will go out there and man up with no help over the top for 65 plays against Calvin Johnson," Whitt Jr. said. "There's nobody that can do that. He's just too talented. So you're going to have to have help, you're going to have to put people over the top, you're going to have to disguise coverages, you're going to have to roll people under him."
The Packers will use multiple defensive backs against Johnson when they play the Lions at noon Sunday at Ford Field. Each defender knows the challenge awaiting in Detroit. They crave the opportunity to measure themselves against the NFL's best.
For each, the approach is different.
Sam Shields doesn't want to make this week more than it is. Sunday is not a "prove it" game, even after signing a four-year, $39 million contract extension in March.
Green Bay signed the fifth-year cornerback for matchups like these. Shields is expected to hold his own against the best in the NFL. He'll see Johnson twice each year for as long as they share a division.
Shields said he's looking forward to the showdown on Johnson's turf.
"At the end of the day, it's all competition," Shields said. "He's a big challenge. You know, a guy like that, you want that. In the NFL, all eyes on you, everybody wants to see what you're going to do against Calvin Johnson."
Shields had his moments against Johnson the last time Green Bay traveled to Detroit. Johnson got his highlights, finishing with six catches for 101 yards and a touchdown. It could've been more.
On third-and-10 in the second half, Shields intercepted a pass in the end zone, holding Johnson to one score.
Shields is expected to be Johnson's primary defender this weekend. He'll get help, but the responsibility of stopping the unstoppable is his.
Shields reverts to his college days, when he played receiver for three seasons at Miami. He said the key to beating Johnson is approaching each pass like the intended target. When the ball reaches its highest point, go get it.
He did well enough for Johnson to walk away impressed after their past battle.
"Sam has great ball skills," Johnson said this week. "I believe he played some receiver when he was at Miami, when he first went there. He is pretty sticky in coverage."
When Johnson lines up in the slot, it could be Tramon Williams' turn to face a longtime rival.
These two have been battling for years. Both entered the league in 2007, playing in the same division. They know each other's ways, the strengths and weaknesses.
Johnson mentions is Williams "slightly bigger" than Shields. Most important, he's got plenty of experience with this specific task.
"He is very smart," Johnson said. "… He knows concepts, he knows offenses, he knows what you are trying to do when he sees certain things. You can expect him to be kind of jumpy sometimes."
Williams doesn't see his old nemesis on the field as much as he used to. Shields has become the Packers' best cover corner. He gets the big assignments.
The Packers have been understandably coy this week about how exactly they'll defend Johnson. The one, universal opinion is it won't be a one-man job.
"It's what we've got to do," Williams said. "When you're facing a guy like that, it's more of a 'we' than an 'I.' It's what we have to do."
Williams said Johnson doesn't intimidate him. Over the years, Williams built a healthy respect. He's had some success. Three seasons ago at Ford Field, Williams helped hold Johnson to 49 yards on four catches.
Later that 2011 season, Johnson exploded for 11 catches and 244 yards at Lambeau Field. A lesson was learned that day.
"At any given time, whether he's in double coverage or triple coverage, he can still make a play," Williams said.
Davon House pulled out all the film.
Johnson vs. Richard Sherman. Johnson vs. DeAngelo Hall. Johnson vs. Shields. He's watched it all.
For House, Sunday will be a first. He has never covered Johnson. Never lined up face to face, looked into his eyes, and felt the nerves.
He's expecting to get his turn in Detroit. On paper, it makes sense. At 6-foot, 195 pounds, House is the Packers' biggest cornerback.
All that film study taught House one thing. No matter what happens, he won't see anyone else like Johnson.
"It's not even close. Not even close," House said. "The closest one to him might be A.J. Green, and A.J.'s still not Calvin. He makes everything look easy. You can tell that whenever the ball's in midair, he feels like he can get it, regardless if there's two or three people on him.
"Special. The man's special. He really is."
— firstname.lastname@example.org and follow him on Twitter @ByRyanWood