Jimmie Johnson and Chad Knaus have been paired together since Johnson entered the Sprint Cup Series as a rookie in 2002. Since then, the duo has formed one of the best driver-crew chief combinations in NASCAR history, winning six championships and 69 races.

Yet as successful as they've been together, the relationship between Johnson and Knaus has been filled with some contentious moments. Following a frustrating end to the 2005 season, team owner Rick Hendrick held the infamous "milk-'n-cookies" meeting where he demanded Johnson and Knaus stop acting like petulant children or he'd break them up.

That meeting was the genesis of a run of six championships in eight years.

However, 2014 has been a struggle -- at least by Johnson's high standards -- with any chance of a seventh title ending when he was eliminated from the Chase for the Sprint Cup last weekend at Talladega Superspeedway.

Exasperating the up-and-down season have been some moments of friction between Johnson and Knaus, including a terse exchange mid-race two weeks ago at Charlotte Motor Speedway. All leading to speculation they may soon see their relationship coming to an end.

Not so, Johnson said Friday at Martinsville. The defending series champion expects Knaus to return next season, and if there is a change, it won't be Johnson's doing.

"When Chad decides he's had enough of being the guy on the box, it will be his decision to step down," Johnson said. "As far as I'm concerned, we've made it 13 years in this thing. I want to see it go as long as it can. We're honest with each other and know each other well enough to work through the bad times. It might not be pretty, and I'm sure you guys have heard things on the radio that got your attention. We're like family, and we fight like family.

"It's more of a timeframe of when Chad says, ‘I've put in my time here as crew chief and I need to slow down a little bit.'"

Due to the stress of being a crew chief, Johnson does envision the day when Knaus will move on.

"That day is out there," he said. "I think a crew chief's lifespan is much shorter than a driver's. They live in dog years and drivers can carry on much longer."

Now that they're out of the Chase, the focus has turned to next season. With NASCAR enacting a testing ban, the 48 team will have an opportunity to get a jump on 2015. Johnson also wants to end this season strongly and win races.

"I don't want to be in this position," Johnson said. "But it's great medicine to sit and watch this championship unfold. It's going to motivate me, Chad and all of us on the 48 team. We'll come back next year and be ready to roll."