Kim O'Reilly, CBS Sports

One week after the CBS Sports NASCAR Power Rankings were reset following the end of the regular season, the opening race of the playoffs at Darlington meant another major shakeup in the standings. Unfortunately, that comes at the expense of regular season champion Martin Truex Jr.

Although Truex emerged from the Southern 500 with an 18th-place finish and a 25-point advantage over the cut line, it certainly felt like his race was far worse. It seemed like Truex and his team simply missed the handling of their car the whole weekend, and a mid-race loose wheel during a cycle of green flag stops certainly didn't help matters. That amounted to an inauspicious start to the playoffs for the 2017 Cup champion, who has fallen all the way from third to 15th in the Power Rankings.

The top two in the Power Rankings held serve following Darlington, with Chris Buescher and William Byron continuing to hold the top two spots after they finished third and fourth, respectively. No playoff driver gained more ground than Kyle Larson, whose first Southern 500 victory led to him jumping all the way from 14th to third.

Here's a look at our updated Power Rankings:

1Chris Buescher--You could say Chris Buescher is on fire right now. There have also been two races in the past two years where Chris Buescher's car has been literally on fire in the middle of the race. His average finish in those races? 6.5.
2William Byron--Martin Truex Jr.'s issues at Darlington allowed William Byron to take a step forward in distinguishing himself as the driver to beat for this year's Cup championship. His fourth-place finish at Darlington gave him his 10th top five of the season, two off of his career-high mark of 12 set back in 2021.
3Kyle Larson
Kyle Larson picking up his third win of the 2023 season in the Southern 500 bodes well for his chances of getting back to the Championship 4. It took him all the way until Homestead to get his third win of 2022, and by that point he had already been eliminated from championship contention.
4Tyler Reddick
There are probably some hardcore South Carolina fans who were glad Tyler Reddick didn't win at Darlington. Reddick winning in his Tar Heel blue Jumpman car the night after UNC beat the Gamecocks in the Duke's Mayo Classic would surely have stung a little.
5Brad Keselowski
Brad Keselowski has had a top-10 finish in six of the last seven oval races, which sure makes it feel like his return to Victory Lane is coming soon. Perhaps it happens at Kansas, where Keselowski won in 2011 and again in 2018.
6Denny Hamlin
Since Kansas went from one to two race dates in 2011, only one driver -- Martin Truex Jr. in 2017 -- has ever swept both races in a single season. Denny Hamlin, who has four straight top-five finishes at Kansas, can join him this weekend.
7Bubba Wallace
Bubba Wallace took a thinly-veiled shot at Kyle Petty -- who insinuated that Wallace declining an interview before Daytona was a reflection of fragility on his part -- in his pre-race interview with NBC Sports. But despite finishing seventh in the Southern 500, Wallace seemed needlessly hard and down on himself after he got into Joey Logano at the end of Stage 1 -- which somewhat supports the idea Wallace can get too emotional about things.
8Kevin Harvick
While it was the correct call by the letter of the law, I will say it seemed pretty ridiculous to penalize Kevin Harvick for coming to pit road as he was committed to come in as the caution came out and as it was too late for him to decommit. Especially given that the caution was caused by the driver he had been racing for the lead before that happened.
9Ross Chastain
The Southern 500 marked only the second top five Ross Chastain has earned since the first race at Kansas all the way back in May. That was somewhat overshadowed by him socking Noah Gragson in the face, and Gragson won't be back at Kansas this time after losing his ride at Legacy Motor Club.
10Ryan Blaney--A ninth-place finish in the Southern 500 gave Ryan Blaney his 13th top-10 finish of the season, which shows up pretty well on the stat sheet. But that's counteracted by the fact that Blaney only has four top-five finishes, which is on track to be his lowest since he was driving for the Wood Brothers back in 2017.
11Chase Elliott
I had to do a double-take when I was going over the official results from NASCAR Statistics, but there's a (P) next to Chase Elliott's name just like the drivers who qualified for the playoffs. That's because Elliott's No. 9 team is in the owner's points playoffs, which is reflected on the stat sheet despite Elliott missing out on a championship run.
12Kyle Busch
Kyle Busch's recent results at Kansas can be described as feast or famine. He won there in the spring of 2021 and finished third in the spring race the next year, but he also has three finishes worse than 26th including a DNF back in May.
13Joey Logano
Despite recovering from a bent toe link to finish 12th, Joey Logano now stands just three points above the playoff cut line entering Kansas. For what it's worth, the defending Cup Series champion has never -- not once -- been eliminated from the playoffs in the Round of 16.
14Ricky Stenhouse Jr.
Ricky Stenhouse's race in the Southern 500 was a testament to his assertion that he isn't just going to be one-and-done in the playoffs. The No. 47 team fought through adversity after an early speeding penalty and finished 16th, putting them just four points below the cut line entering Kansas.
15Martin Truex Jr.
Forget everything I said about how Martin Truex Jr. was probably going to dominate the Southern 500. The No. 19 missed it, never had it, and quite frankly Truex was lucky to salvage his race with an 18th-place finish.
16Christopher Bell
Unfortunately for Christopher Bell, he may have taken the lead in the clubhouse among candidates for a surprising first-round exit after a rough Southern 500. He'll have to bounce back at Kansas to lessen the chances of that, and he had top-five finishes in both races there in 2022.
17Michael McDowell
Two years after his first playoff run was set back by a crash in the Southern 500, the same thing happened to Michael McDowell again. He was the only playoff driver to fail to finish the race, putting him in a deep points hole entering Kansas.
18Erik Jones
Erik Jones surely wishes he could have a do-over of his season, as we're starting to see results out of him that more closely resemble the way he ran for much of 2022. Jones had a top-five car at certain points and finished 10th at Darlington, his fourth top 10 since June.
19AJ Allmendinger
Amid chatter about what series he might race in next season, AJ Allmendinger enjoyed a nice 13th-place run in the Southern 500. For The Dinger, that marked his first top-15 finish on an oval since he ran third at Atlanta back in July.
20Aric Almirola
Speaking of drivers who could use a season do-over, Aric Almirola belongs in that category as well. He continued his second half turnaround with yet another top-15 finish at Darlington.
21Corey LaJoie
One thing that caught my attention in the opening laps at Darlington was some close quarters racing between Corey LaJoie and Carson Hocevar, which almost ended in Hocevar getting turned. If you'll remember Gateway, Hocevar drove LaJoie's No. 7 while LaJoie was filling in for Chase Elliott in the Hendrick Motorsports No. 9.
22Chase Briscoe
This weekend at Kansas will mark the first time Chase Briscoe has had Richard Boswell as his crew chief for a race at Kansas in three years. The last time those two were paired together at this track, Briscoe won an Xfinity Series race in the fall of 2020.
23Alex Bowman
Only what must have been an hour after Travis Mack took a couple of shots at Alex Bowman on Twitter, the two proceeded to cross collaborate on selling T-Shirts, with Bowman saying the post-race meeting about their beef would take place at Arby's. That was a fast way to resolve this.
24Daniel Suarez
Quick Spanish lesson here after Daniel Suarez's comments on a "dumb move" by Alex Bowman: If you want to call someone dumb, you can call them menso, tanto, tarado, mentecato -- or you can call them estúpido, which will probably sting for even the most uncultured of fools (Saw it back home in White Plains, N.Y. once).
25Austin Cindric
Austin Cindric's first weekend reunited with crew chief Brian Wilson was looking good until he and Ty Gibbs crashed together midway through the Southern 500. Cindric had a great 15-lap average in practice and was a borderline top-10 car early, suggesting we could see some good things from Cindric over the remainder of the season.
26Ty Gibbs
Speaking of that crash between Cindric and Gibbs, that was two out of the last three Xfinity Series championships coming together in the middle of Turns 1 and 2. Only 2021 champion Daniel Hemric missed out on the fun, as he was long gone after finishing 10th on Saturday.
27Austin Dillon
Would you believe it, Austin Dillon showed up at the front of the field in an important race! Dillon got some stage points on strategy at the end of Stage 2, but later got together with Todd Gilliland on his way to a pedestrian 20th-place finish.
28Justin Haley
Justin Haley makes it back in the Power Rankings, mostly by virtue of issues for other drivers who were toward the back end of the standings. He hasn't scored a top-20 finish since New Hampshire in July, which coincides with his announcement that he's moving to Rick Ware Racing next year.
29Todd Gilliland
Todd Gilliland's late race spin was a setback for him, but it ended up being much worse for Front Row Motorsports as a whole. The fact that the chain reaction from Gilliland's spin led to terminal crash damage for teammate Michael McDowell surely doesn't feel good for Gilliland at all.
30Harrison Burton
I'm putting Harrison Burton back in the Power Rankings in part out of pity over what happened to him at Darlington. He was knocking on the door of the top 10 when Alex Bowman and Daniel Suarez took each other out in front of him, and he got collected as a completely innocent bystander.