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What to know about round one of the NASCAR In-Season Challenge.

The NASCAR Cup Series is about to kick off the second year of the In-Season Challenge. Made up of 32 drivers, the In-Season Challenge is a five-race, elimination-style bracket challenge, where only one will be left standing.

Sonoma Raceway will be the site of the opening round of the In-Season Challenge this Sunday. For fans unfamiliar with how the bracket works, who is seeded where, and who is facing whom in the first round, here is a full breakdown.

Full breakdown of In-Season Challenge Round 1

The In-Season Challenge starts with the top 32 drivers in the NASCAR Cup Series points standings. For the opening round, there are 16 head-to-head matchups, with the highest finisher of the matchup advancing to the next round. Round two is set to take place at Chicagoland Speedway on July 5.

The bracket has two sides. Here is a look at the left side of the bracket’s opening round matchups and the driver seedings. Seeding is based on a driver’s position in the Cup Series points standings. 

Of the four groups of four drivers, the winners will advance and face each other in the next round.

No. 1 Tyler Reddick vs No. 32 Alex Bowman

No. 16 Austin Cindric vs No. 17 Brad Keselowski

No. 8 Daniel Suarez vs No. 25 Todd Gilliland

No. 9 Carson Hocevar vs No. 24 Zane Smith

No. 12 Chase Briscoe vs No. 21 A.J. Allmendinger

No. 5 Ty Gibbs vs No. 28 Austin Dillon

No. 13 Bubba Wallace vs No. 20 Michael McDowell

No. 4 Chase Elliott vs No. 29 Noah Gragson

The right side of the bracket’s opening round matchups and the driver seedings go as follows. Like the left side of the bracket, it is four groups of four drivers, with the winners of their Sonoma matchups facing each other in round two. 

No. 2 Denny Hamlin vs No. 31 Ty Dillon

No. 15 Erik Jones vs No. 18 Joey Logano

No. 7 Chris Buescher vs No. 26 John Hunter Nemechek

No. 10 Christopher Bell vs No. 23 Ross Chastain

No. 11 William Byron vs No. 22 Ricky Stenhouse Jr.

No. 6 Kyle Larson vs No. 27 Riley Herbst

No. 14 Shane van Gisbergen vs No. 19 Ryan Preece

No. 3 Ryan Blaney vs No. 30 Josh Berry

How the In-Season Challenge will unfold after Sonoma

Following Sonoma, 16 drivers will remain alive in the In-Season Challenge. Chicagoland Speedway is the site for round two, where there will be another eight head-to-head matchups. 

Only eight will remain for round three, which takes place at the EchoPark Speedway. After another four head-to-head battles, four drivers will remain for round four at North Wilkesboro.

At North Wilkesboro, there will be two head-to-head matchups to decide who will battle in the final round in the Brickyard 400 at Indianapolis Motor Speedway. The highest finisher of the two drivers of the final round will be the winner of the In-Season Challenge and receive $1 million.

Last year, Ty Gibbs made his way through the 32-driver bracket to win the inaugural In-Season Challenge. In the final round, Gibbs bested Ty Dillon, who made it to the finals despite entering the bracket as the lowest seed.

The Toyota/Save Mart 350 at Sonoma is scheduled to begin at 3:30 p.m. Eastern time. It can be watched on TNT or listened to on the Performance Racing Network.