If Jimmie Johnson wins a record eighth NASCAR Cup Series championship, it won't be with Chad Knaus as his crew chief.

Kevin Meendering, crew chief for Elliott Sadler in the Xfinity Series, will take over the No. 48 team starting in 2019, while Knaus will become crew chief for Hendrick Motorsports driver William Byron, according to a team news release.

Knaus and Johnson began working together in Johnson's rookie season in 2002, and they won five consecutive Cup championships together from 2006 to 2010 as well as championships in 2013 and 2016. They have struggled the past two years, however, with Johnson finishing 10th in the standings last year and failing to advance out of the first round of the playoffs this year.

"It's no secret that Chad and Jimmie have experienced their ups and downs over the years," team owner Rick Hendrick said in a news release. "They're fierce competitors, great friends and have immense respect for one another.

"They also fight like brothers. All three of us agree it's finally time for new challenges and that a change will benefit them and the organization."

Jimmie Johnson, left, and crew chief Chad Knaus have won seven Cup Series championships together, but their pairing is ending after this season. Knaus will take over the team of William Byron, with Jeff Meendering taking over Johnson's No. 48 team. Jerry Markland/Getty Images

Johnson, who ranks tied for sixth all time with 83 career Cup victories, is on a 53-race winless streak.

Johnson shared his thoughts on the change via Twitter.

Chad and I have had unimaginable success together and I'm grateful for his friendship. I can't thank him enough for his dedication to success and the drive to win. I'm looking forward to what the future holds for the entire @TeamHendrick organization. pic.twitter.com/zA8fse6XfI — Jimmie Johnson (@JimmieJohnson) October 10, 2018

Meendering has spent the past three years at HMS affiliate JR Motorsports and has guided Sadler to three wins and 38 top-5 finishes.

"Over the last couple of years, he's been one of the most sought-after talents in the garage," Hendrick said. "Kevin is an impressive person who came up in our organization and will hit the ground running on Day 1. We already know how well he works with our people and that he's a respected, forward-thinking crew chief.

"Having worked with a veteran driver like Elliott Sadler for three years is extremely valuable experience. He's the right fit for Jimmie at the right time."

Knaus signed a two-year contract extension during the summer and now will be paired with Byron, who sits 22nd in the Cup standings as a rookie and turns 21 in November. The move "reunites" Knaus with the team that gave him his first full-time Cup job in 1993: the HMS No. 24 crew.

"You can't quantify how much Chad's leadership and championship experience will benefit William, who is a special talent," Hendrick said in the release. "The two of them are a great match, and I'm excited to see what they can do together.

"Chad has the Rainbow Warriors pedigree and truly appreciates the history of the No. 24. I've asked him to build another winner and given him the green light to put his stamp on the team and do it his way."

Only the crew chiefs will change roles. The remainder of the team personnel will stick with their current drivers.

"Chad and Jimmie will go down as one of the greatest combinations in sports history," Hendrick said. "They defied the odds by performing at a championship level for longer than anyone could've possibly imagined.

"What they've accomplished together has been absolutely remarkable and will be celebrated for generations. This has been an incredible, storybook run."

Current Byron crew chief Darian Grubb will move into a technical director role in the HMS engineering and vehicle development department.