Six-time and defending NASCAR champion Jimmie Johnson dismissed the idea that there is any tension with crew chief Chad Knaus after the two were overheard bickering on their team radio.

Johnson and Knaus revealed discord during Saturday night's race at Charlotte Motor Speedway, where Johnson dropped to the brink of elimination from NASCAR's championship race. The two were terse with each other at points during the race, but Johnson dismissed it Friday as frustration over how the Hendrick Motorsports team is performing.

"Frustration is high, for sure," Johnson said. "Chad and I, in our relationship, have had these peaks and valleys. We've had times where there has been plenty of frustration on the radio. But who we are and what we are as a team and the way our relationship works and us moving forward — things are still as they have always been.

"It isn't fun, and I'm sure people hear plenty of colorful things from drivers and crew chiefs during the course of a race," he said. "Last weekend there was plenty of color on our channel. It just comes with the territory. We're not happy with where we're at, and I don't know why we would be."

Johnson needs to win Sunday at Talladega Superspeedway to remain eligible for the Chase for the Sprint Cup championship. He's trying to win a record-tying seventh championship.

Johnson and Knaus were almost split by team owner Rick Hendrick following the 2005 season, but Hendrick made them hash out their differences over a snack of milk and cookies. They went on to win a record five consecutive titles.

He has three wins this season, and two career victories at Talladega. Johnson said he and Knaus are approaching Sunday with a must-win mentality.

"Granted, it's a tough one and a lofty goal," he said. "There are many other guys out there with the same goal, not only from a Chase situation but also trying to win a race this year. I've got a lot of work ahead for myself and this team this weekend, so we're ready for the challenge. We'll get out there to work and see what happens."