The Vikings returned from their bye week Monday morning and went through a light, 55-minute practice to get back into the swing of things as they prepare for a weekend trip to Chicago. Missing from the workout, however, were receivers Percy Harvin and Michael Jenkins.

Harvin still is sidelined because of a sprained left ankle, an injury he suffered in the second half of a Week 9 loss in Seattle. Harvin did not play against Detroit on Nov. 11 and stayed behind in the Twin Cities last week to receive treatment on the ankle.

Jenkins, meanwhile, is dealing with a foot problem that arose after he headed home for the bye. Coach Leslie Frazier said the veteran receiver is experiencing soreness and tenderness and was given Monday off as a precaution.

The Vikings still are hoping Harvin can show enough to be ready for Sunday's game with the Bears. The swelling in his ankle has subsided significantly, according to Frazier. Now it's a matter of Harvin getting comfortable putting pressure on the ankle.

Frazier's hope is to have Harvin back on the practice field in a limited capacity Wednesday. But it's uncertain whether that wish will come true.

"We'll see where he is on Wednesday and hopefully we'll be able to see him do a little bit," the coach said.

Improvement needed While the players had some time off, the coaches spent much of the bye doing some self-scouting. So what conclusions were reached for the offense?

"They talked about what we needed to work on, and the big thing is our turnover differential," quarterback Christian Ponder said. "And our Red Zone [offense]. Those are two things that we've got to work on, especially with our schedule stacked up."

And what is the key to improvement in those areas? Execution, of course.

"We've just got to keep working on it and finding ways to make it happen," Ponder said. "When we look back at the film and what we did wrong, it just goes back to execution and getting through my reads quicker and being able to check the ball down and not forcing things outside."

Etc. • The bye came at a good time for defensive end Jared Allen, who had struggled because of a groin pull. "I'm probably 75 [percent]," he said. "But you just work through it. Nobody is 100 percent this time of year."

• Nose tackle Letroy Guion was back at practice and seemed to be moving around well after sitting out the Week 10 victory over Detroit because of a turf toe issue.

• The Vikings replaced the turf in their indoor practice facility during the bye week. And Frazier said the new field, identical to the playing surface at Mall of America Field, had the players excited.

"I appreciate our ownership getting that done coming out of the bye," Frazier said. "It's kind of refreshing for our players to come back and practice on the surface that they play on. So they were pretty excited about that. Especially some of our veteran guys."