NASCAR Toyota/Save Mart 350 preview: Favorite, underdog, top storylines

On Sunday, the stars of the NASCAR Cup Series face their final road course challenge of the season in the running of the Toyota/Save Mart 350 at Sonoma Raceway (3:30 p.m. ET, TNT, HBO Max, PRN Radio, SiriusXM NASCAR Radio).

Here's what you need to know ahead of the 18th race of the regular season.

Favorite: Shane van Gisbergen (-155, per BetMGM)

Even though van Gisbergen had to settle for sixth in Saturday's qualifying session, he remains the clear favorite in "Wine Country" after leading 97 of the 110 laps from the pole in a dominant effort last season.

Coming off a disappointing 38th-place finish at Naval Base Coronado, Sonoma represents the biggest race of van Gisbergen's career after slipping below the provisional 16-driver "Chase" field. His weekend is already off to a great start after winning Saturday's O'Reilly Auto Parts Series race, and it would be stunning if he is not the driver to beat on Sunday.

Underdog: Chris Buescher (+3000, per BetMGM)

Don't look now, but Buescher, one of the sport's most consistent and underrated drivers, finds himself seventh in points after another steady weekend in San Diego with points in both stages and a sixth-place finish to show for his efforts.

Buescher also has a prior road course win at Watkins Glen in 2024 when he outdueled van Gisbergen on a thrilling final lap. When you combine Buescher's consistency on road courses with his Sonoma history, which includes three top fives and a 13.1 average finish, he is a sneaky contender for the win on Sunday.

Ty Gibbs rockets to pole in final seconds of qualifying

In a qualifying session that featured some rear grip issues and a few missteps from drivers, the most significant coming when Bubba Wallace went wide coming out of Turn 10 and suffered heavy nose damage, it also featured some surprises at the top of the leaderboard.

Although Carson Hocevar appeared to be on his way to a shocking road course pole, Ty Gibbs delivered the fastest lap at the last second to claim his third career Cup Series pole. That continued Gibbs' strength in qualifying at Sonoma with an average starting position of 7.3, but it remains to be seen if he can stay there with just one top 10 in three starts.

Tyler Reddick looking to maintain points lead amid Denny Hamlin's recent surge

Just six races ago, following the Watkins Glen race on May 10, Reddick held a 129-point lead and looked to have the regular-season title locked up. After a stretch that included a three-race winning streak for Hamlin and two finishes of 25th or worse in the last three weeks for Reddick, that advantage now stands at just eight points.

Reddick only qualified 11th, but with four road course wins to his credit to Hamlin's one, there is no better time than now for him to respond to the recent adversity after placing inside the five, 10 and 15-lap averages in practice.

Year 2 of the In-Season Challenge set to begin

One season after Gibbs became the inaugural winner of the In-Season Challenge, the head-to-head, bracket-style competition's five-race stretch takes the green flag at Sonoma.

From the top seed Reddick all the way down to No. 32 seed Alex Bowman, some matchups are more intriguing than others in the first round. With a road course, 1.5-mile track (Chicagoland), drafting-style track (EchoPark Speedway), short track (North Wilkesboro) and 2.5-mile track (Indianapolis), a diverse slate awaits drivers as they battle for the $1M prize.