The second installment of NASCAR’s In-Season Challenge returned with a bang at Sonoma Raceway as power steering issues eliminated No. 1 seed Tyler Reddick and flipped the bracket upside down.

The field is now whittled down to 16 drivers and eight head-to-head matchups as NASCAR makes its first stop at Chicagoland Speedway since 2019 on Sunday (6 p.m. ET, TNT, HBO Max, MRN Radio, SiriusXM NASCAR Radio).

While some matchups may not be as even on paper as others, the same does not apply to a trio of battles that stand out above the rest. With that in mind, here are three must-see battles in the second round of the In-Season Challenge.

No. 11 seed William Byron vs. No. 6 seed Kyle Larson

This matchup of Hendrick Motorsports teammates was one that many were expecting in the second round, and both drivers ensured it would happen with finishes of fourth and 12th, respectively, at Sonoma. 

Larson is still searching for his first win since Kansas in May 2025, but four straight top-five finishes and five in his last six races suggest he is on the cusp of returning to victory lane. The two-time champion has never won a Cup race at Chicagoland, but he has back-to-back runner-up finishes and a ridiculous 6.2 average finish there.

Unlike Larson, who is also fifth in points, Byron is much farther down in 12th with only two top 10s in his last six races. That is far from the performance you would expect from the 2025 regular-season champion, but with top 10s at all three 1.5-mile tracks this season, this has the potential to be the most competitive matchup in the second round.

No. 12 seed Chase Briscoe vs. No. 5 seed Ty Gibbs

Let’s keep the theme of teammate battles going with a fascinating head-to-head between a pair of Joe Gibbs Racing drivers who were next in line behind Shane van Gisbergen at Sonoma and could be battling for the race win on Sunday.

In a season that was defined by mistakes and missed opportunities early on, Briscoe has turned that around with three top 10s in his last five races. He has no Cup Series history at Chicagoland, but with an ARCA Menards Series win there in 2016, he is no stranger to getting around the 1.5-mile track in Joliet, Illinois.

Gibbs had arguably the best drive of the race at Sonoma, sacrificing track position for stage wins and driving back through the field with relative ease. He, too, does not have Cup Series experience at Chicagoland, but Gibbs has been a threat almost everywhere he goes and that should not change on Sunday.

No. 14 seed Shane van Gisbergen vs. No. 3 seed Ryan Blaney

Despite the challenge from Briscoe in the closing laps, van Gisbergen did the inevitable and won his eighth road course race at Sonoma. Now, with only ovals remaining on the schedule, how will he fare on layouts that he is still learning at?

Van Gisbergen has made strides on ovals this season, finishing 11th at Charlotte and a career-best fifth on an oval at Nashville. Blaney, meanwhile, has the most top 10s in the series (13) and participated in the Goodyear tire test at Chicagoland back in April. 

This matchup is more about seeing how far van Gisbergen has come on the intermediates and the fact that the unpredictable drafting-style racing of EchoPark Speedway that follows could give him a path to the semifinals of the In-Season Challenge if he can pull the upset against Blaney.