ALLEN PARK -- Detroit Lions quarterback Matthew Stafford and receiver Calvin Johnson were touchdown moguls last season.

The combo has struggled to duplicate that success in 2012.

Four games into this season, Stafford has not thrown a touchdown pass to Johnson. Detroit's standout receiver has only one touchdown reception this year, and that was from backup quarterback Shaun Hill. Stafford and Johnson's inability to connect in the end zone is one reason why Detroit has a 1-3 record heading in the bye week.

It also is an area players and coaches believes needs improvement.

"I think everybody's game plan is starting with, 'let's try to keep them from doing that',"Lions coach Jim Schwartz said. "That's definitely part of the situation. It's not to say that we can't be effective and we can't score on offense. We don't have any goals on how many touchdowns Calvin and Matthew are going to connect for. What we want to do is we want to score.

"Whether it's Calvin or anybody else, our goal is the get in the end zone and score. We don't play fantasy football. When we're trying to score we don't care who does it."

Last year, Johnson caught 96 passes for a league-best 1,681 yards and 16 TDs, joining Jerry Rice and Randy Moss as the only players in NFL history with at least 95 receptions, 1,600 yards and 15 touchdowns in a season. He became the only player in league history to catch nine TDs in his first five games of a season. Johnson's performance resulted in him getting an an eight-year contract worth up to $132 million during the offseason.

After throwing 5,038 yards, 41 TDs and 16 interceptions last season, Stafford has fewer TD passes (three) than interceptions (four) this year. If Stafford and Johnson stay on this pace, it will be hard for either player to repeat last year's statistical success.

"We were 5-0 last year because we were able to get into that end zone eight times in first four games," Johnson said. "That helped out a lot. We were able to convert in the red zone. Like I said, teams are not playing us different, so we got to find a different way of going about it."

Detroit's struggles to score this season can be attributed to its opponents.

Teams are dropping back in coverage, and Lions coaches have struggled to adjust to this year's defensive coverages, while players are struggling to execute. Johnson was targeted 12 times for the third-straight game last week against Minnesota, but had only five receptions for 54 yards, both season lows. In four games, he has 29 receptions for 423 yards and a touchdown pass from Hill.

"We've obviously put some shots in the game," Stafford said. "First play of the game last week we threw one down there, threw another one on third down; down the field to him. Minnesota did a good job of taking it away and breaking up some passes we threw down the field to Calvin. It's not only him. It's other guys.

"We've gotten down the field against ... When they try to take Calvin away with certain coverages, we've actually been really efficient and had some explosives, too. We just got to keep drives alive on third-down and score it when we get down there in the red zone."