Dale Earnhardt Jr.'s return to Michigan isn't off to a great start.

Earnhardt, who won at Michigan International Speedway in June to snap a four-year losing streak, will have to start from the back Sunday in the NASCAR Sprint Cup race. He rubbed against the wall in practice Saturday and will need to go to a backup car.

"We were making some changes on the car and got the car too loose, and it just came out from under me in the corner," Earnhardt said. "I probably was running harder than I should have been in practice."

Series points leader Jimmie Johnson also will be in back because of an engine change.

Earnhardt tested his backup car at MIS, back in June.

"We know a lot about the car here at this particular track, where in most cases you don't. So we have that going for us," Earnhardt said. "We should be able to put a car out there that's relatively in the ballpark. Other than just starting in the back, I don't think that it's hurt our chances too much."

Johnson said his team discovered an issue before practice Saturday and decided to change the engine.

"We probably could have run some of this practice, but I think we had to change the engine regardless," he said. "We didn't want to oil the track or create an issue and crash our car."

Johnson was third in qualifying Friday. Earnhardt was 22nd.

Earnhardt broke through at this track in June, winning for the first time in 144 Cup races. He's fourth in the points standings and has nine top-five finishes, but lately he has had his share of problems.

He led the points race even after finishing 32nd at Pocono two weeks ago — he was forced to the garage at one point because of a busted transmission. Then last weekend at Watkins Glen, he was in the top 10 before a late spin sent him on his way to a 28th-place showing.

The last driver to sweep the two Cup races at MIS was Bobby Labonte in 1995. Earnhardt has nine top-10 finishes in 26 starts at the track.

"Getting over that hurdle, getting that first win does a lot to relieve you," Earnhardt said. "It reassures you that your team can win. I think if we were still winless, we would still feel a bit snake-bitten, or somewhat cursed I guess in a way. That might mess your psyche a little bit, mess with you mentally. But once you do break through that barrier, it definitely gives you a reason to believe that you can do it again."

He'll have his work cut out for him Sunday after his practice mishap, but the victory two months ago has helped Earnhardt's confidence.

"To me Dale has been really focused and really into everything that I have been part of this season with him," said Kasey Kahne, Earnhardt's teammate with Hendrick Motorsports. "He's into the racing thing as much as I've seen him. I haven't been really close with Dale over the years, but I've known him and been friends with him. I think he's as passionate and into the racing as I've seen him right now, so that's good to see."

Earnhardt had some good news Friday when the Army National Guard extended its relationship with Hendrick Motorsports. The National Guard will stay on as a sponsor of Earnhardt's No. 88 Cup team.

That took some of the focus off his recent struggles. Another good showing at MIS would help too.

"There is a little bit of added pressure to go back out and have the same performance and run the same," he said Friday, before qualifying. "I know that is not always likely."