NASCAR investigating driver for late-race shenanigans that helped knock the defending champ out of the playoffs

• Christopher Bell won a dramatic race at the Charlotte Roval to advance to the Round of 8 in NASCAR's playoffs.
• Stewart-Haas' Chase Briscoe used a daring late pass to avoid elimination and advance on points.

Chase Briscoe of Stewart-HAAS Racing pulled off a dramatic move to avoid elimination from the playoffs and knock out defending champion Kyle Larson. Now, NASCAR wants to know if he got a little too much help from a teammate.

After the race, NASCAR announced that it is investigating a last-lap move by Cole Custer that allowed Briscoe to pick up enough points to advance and whether the team told Custer to interfere.

"NASCAR is reviewing data, video and radio transmissions from the 41 car following its incident on the backstretch during the final lap," NASCAR said. "NASCAR will communicate the results of the review early this week. Any potential penalties would not affect the Round of 8 field."

The last sentence is important, as it suggests that regardless of the findings, Briscoe will remain in the playoffs and Larson will not.

Dramatic final laps shuffled the playoff field

Christopher Bell came from behind to win the dramatic race at the Charlotte Roval, where the final laps saw several lead changes and a constant reshuffling of which eight drivers would advance to the next round.

Winning the race was Bell's only shot at advancing in the playoffs. Doing so effectively meant that four drivers — Larson, Briscoe, Daniel Suarez, and Austin Cindric — were battling for the final spot, with Larson leading that group with three laps to go.

With two laps to go, Briscoe spun and fell to the back of that group, seemingly out of the playoffs. However, the racing gods intervened, and a red flag stopped the race to repair a broken curb. This allowed Briscoe to pit for fresh tires before starting the three-lap overtime.

Briscoe still needed to make up 19 spots in three laps to catch Larson. Several collisions and spins — including one by Cindric, which knocked him out of contention — helped Briscoe make up most of those spots.

However, it was the final pass just before the checkered flag that clinched Briscoe's advancement and Larson's elimination and raised the eyebrows of NASCAR officials.

As Briscoe (14) approached the final chicane, he was tied with Larson and holding the tiebreaker. One more pass would seal the deal. That's when teammate Cole Custer (14) slammed on his brakes a little early, bunching up the pack and allowing Briscoe to fly right by.

At the 55-second mark of this video from Briscoe's car, you can see Custer slide up in front of the green No. 3 car of Austin Dillon, who was forced to ease up on the gas.

Briscoe passed Dillon and Custer, picked up two more points, and clinched the final spot in the Round of 8.

Briscoe credited the final pass to extra air pressure in his new tires, which allowed him to be more aggressive.

"Definitely drove it in way further [into the final chicane] than I had all day just knowing every point was going to matter and got kind of lucky that it stuck, truthfully," Briscoe said.

The move was immediately noticed by NBC commentator Dale Earnhardt Jr., who exclaimed, "Cole Custer throwing a block right there on everybody!"

After the race, Earnhardt added: "I think Briscoe was committed to overrunning this braking zone, but I believe Cole Custer was doing some work as well, to try to help out his teammate, throwing a little block there on the back straightaway."