The first of five weeks of head-to-head battles has trimmed the In-Season Challenge field in half after an eventful Sunday at Sonoma Raceway, and zero perfect brackets remain in the pool of fan predictions. The 16 drivers with hopes of claiming the $1 million prize head this weekend to a Sunday showdown at Chicagoland Speedway (6 p.m. ET, TNT Sports, truTV, HBO Max, MRN Radio, SiriusXM NASCAR Radio), which returns to the NASCAR Cup Series circuit for the first time in seven years.
Here’s where things stand after Challenge Round 1 at Sonoma:
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Sonoma race winner: Shane van Gisbergen secured a weekend sweep of the Cup Series and O’Reilly Auto Parts Series events on the 1.99-mile road course, fending off a stout challenge from Chase Briscoe to prevail in Sunday’s main event. SVG led 74 of the 110 laps in Trackhouse Racing’s No. 97 Chevrolet, landing his second win of the Cup Series season and his second straight at Sonoma. He advanced to the In-Season Challenge’s second round over No. 19 seed Ryan Preece, who placed a respectable eighth.
Who advances to Round 2
Advancing with the 14th-seeded van Gisbergen to the next round are: (2) Denny Hamlin, (3) Ryan Blaney, (4) Chase Elliott, (5) Ty Gibbs, (6) Kyle Larson, (7) Chris Buescher, (9) Carson Hocevar, (10) Christopher Bell, (11) William Byron, (12) Chase Briscoe, (15) Erik Jones, (16) Austin Cindric, (20) Michael McDowell, (25) Todd Gilliland, and (32) Alex Bowman.
The top upset from first-round action was Bowman, who rolled into the Round of 16 with a 10th-place effort after top-seeded Tyler Reddick stumbled with mechanical trouble and finished last. The outcome marked the second consecutive year that the lowest seed has advanced, and he’ll face off with Austin Cindric in the second round. Bowman is also the most recent race winner at Chicagoland, where he netted his first Cup Series victory in 2019.
Matchup of the week
(No. 6) Kyle Larson vs. (No. 11) William Byron: This intrasquad matchup of Hendrick Motorsports teammates has some serious star power. A pair of the best on intermediate tracks, Larson and Byron will square off in Round 2 at Chicagoland – both coming off relatively decisive first-round wins at Sonoma Raceway. Larson stomped Riley Herbst in Round 1, finishing fourth while the 23XI Racing driver placed 30th. Meanwhile, Byron finished 12th at the road course compared to 21st for opponent Ricky Stenhouse Jr.
Larson has a momentum advantage, riding a streak of five top fives in the last six races. But as the 2026 campaign inches toward The Chase, this head-to-head battle could serve as an important turning point for the Hendrick organization with both drivers looking for their first wins of the season.
Who’s up
Ty Gibbs, No. 54 Joe Gibbs Racing Toyota. Almost the only thing Gibbs didn’t do Sunday at Sonoma was win, assembling a sizable 54-point day — second only to SVG’s 63 — with a sweep of the stages from the pole position and a third-place result. That equaled a convincing first-round victory over No. 28 seed Austin Dillon, who finished 27th. Gibbs’ path to a second straight In-Season Challenge title will have to go through teammate Chase Briscoe, who makes for an enticing Round 2 matchup after a stellar runner-up finish Sunday.
Who’s down
Todd Gilliland, No. 34 Front Row Motorsports Ford. Gilliland survived a bumpy Sonoma ride, including a pair of run-ins with 23XI Racing’s Bubba Wallace and Riley Herbst in Stage 2. He finished where he started in 29th place, but it was just enough to advance over 31st-finishing Daniel Suárez, a former Sonoma winner whose race went awry after a first-stage flat. Gilliland is among a handful of drivers heading into unknown territory for their first Cup Series start at Chicagoland, and he’ll face off with No. 9 seed Carson Hocevar in a second-round test.
Contributing: Nate Solomon