DOVER, Del. (AP) - Jimmie Johnson has a championship to race for, and he's grateful that his rookie teammate understands to race hard - but not get in the way.

Johnson barely hung on to beat teammate Kyle Busch, then credited the rookie for helping him win Sunday at Dover International Speedway, a victory that vaulted Johnson into the lead in the Chase for the championship.

''He was all over me at the end, and that's the way it should be,'' Johnson said. ''I've got to thank Kyle for being such a good teammate and racing me clean at the end.''

Johnson held off Busch by about a car-length. That they were so close at the end was a tribute to Busch, Johnson said.

''They were up here testing two weeks ago and we used their information,'' Johnson said. ''I don't think Hendrick Motorsports had any new data on the track.''

Busch badly wanted his second career victory, but knew he had done all he could. He said there were no team orders preventing him from trying to beat Johnson.

''We were a little too tight at the end and couldn't get the fresh air we needed,'' Busch said. ''I was hoping he might be little looser and chase up the track.''

Tony Stewart, the Nextel Cup points leader for the last seven races, battled an ill-handling car en route to an 18th-place finish. The outcome also ended his streak of 13 straight top-10 finishes that included five victories.

''Obviously, something happened today,'' Stewart said. ''This wasn't the way our car drove yesterday. But we'll be fine. We'll get caught up.''

There would be no perfect weekend for Ryan Newman, who won poles for both races here and was coming off a victory in a Busch Series contest Saturday. Newman won the opening event in the Chase a week earlier, outdueling Stewart in a stirring finish at New Hampshire International Speedway.

The victory in the MBNA 400 was the third this year for Johnson, who now leads Rusty Wallace by seven points after two of 10 races in the Chase among the top-10 drivers. Johnson also won for the third time at Dover and 17th overall.

Stewart came to The Monster Mile 20 points ahead of Greg Biffle, who won here in June.