CONCORD, N.C. — Matt Kenseth, usually so calm and composed, lost his cool and attacked Brad Keselowski at Charlotte Motor Speedway.

If Kenseth is fighting, then tempers are certainly running quite high. They reached a boiling point in the aftermath of Saturday night’s race as Keselowski, Kenseth, Dale Earnhardt Jr. and Jimmie Johnson all saw their championship hopes fade to near-desperate status.

The pressure is on — every week — in NASCAR’s new championship format, and the frayed nerves unraveled on the track, on pit road and in the garage. Denny Hamlin had to be restrained from going after Keselowski, but Kenseth got to the 2012 champion in the dark alley-like area between a pair of Team Penske haulers.

Kenseth quickly approached Keselowski from behind and nearly tackled him. He had Keselowski wrapped in his arms when crew members quickly peeled him off, and Keselowski crew chief Paul Wolfe pulled Kenseth out of the scrum in what appeared to be a choke hold.

As race winner Kevin Harvick celebrated in Victory Lane, activity in the garage came to a near-halt as drivers and crews watched replays of the melee.

That was at the root of the post-race Charlotte activities: There is no room for error in the Chase, and a bad night will put a driver on the brink of elimination.

Kenseth, who struggled for large portions of the race and was penalized by NASCAR before the start for an unapproved adjustment made to his car, was incensed that Keselowski hit his car on pit road after the checkered flag. Kenseth had already taken off his seatbelts and lowered his window net, and he felt the contact from Keselowski could have caused injury.

“If you want to talk about it as a man, try to do that,” Kenseth said.

For his part, Keselowski said the hit on Kenseth was warranted because Kenseth had driven across his nose under a caution with six laps remaining. That contact caused front-end damage that Keselowski believed contributed to his 16th-place finish. The two had an earlier incident while racing for the lead when Kenseth was squeezed into the wall while he attempted to pass Keselowski.

Hamlin was upset with how Keselowski raced him for position with two laps remaining. Hamlin felt Keselowski pushed him too hard into a corner, contact that sent both drivers plummeting in the field.

Hamlin admitted to brake-checking Keselowski during the cool-down lap, and Keselowski retaliated with a failed attempt to spin Hamlin.

That’s when Keselowski set his sights on Kenseth, hitting him on a busy pit road.