The NASCAR Cup Series championship picture changed dramatically Sunday at Sonoma Raceway.A power steering failure dropped Tyler Reddick to a 36th-place finish, opening the door for Denny Hamlin to reclaim the regular-season points lead despite finishing just 26th himself. Hamlin now sits atop the standings with 719 points, one ahead of Reddicks 718 entering next weekends race at Chicagoland Speedway.Elsewhere, Shane van Gisbergens dominant Sonoma victory vaulted him three spots in the standings, while Ty Gibbs continued his recent surge with another podium finish.Denny Hamlin Edges Tyler Reddick for the Championship LeadHamlin leaves Sonoma with the narrowest possible advantage.The Joe Gibbs Racing veteran now leads the standings by a single point after one of the biggest momentum swings of the season. Reddick entered Sundays race atop the standings, but mechanical problems on the No. 45 Toyota left him multiple laps down before he limped home in 36th.While Hamlin didnt have the type of race that typically produces a points lead, Sonomas attrition at the front of the championship battle was enough to put the No. 11 team back in first.The top 10 in the Cup Series standings after Sonoma:Denny Hamlin 719Tyler Reddick 718 (-1)Ryan Blaney 615 (-104)Ty Gibbs 589 (-130)Kyle Larson 571 (-148)Chase Elliott 554 (-165)Chris Buescher 518 (-201)Carson Hocevar 509 (-210)Daniel Suarez 484 (-235)Christopher Bell 472 (-247)Shane van Gisbergen, Ty Gibbs Among Sonomas Biggest WinnersSonoma produced several notable movers throughout the standings.Fresh off his second victory of the season, Shane van Gisbergen climbed three positions to 14th in the standings. The Trackhouse Racing driver now has two wins through 18 races and continues building momentum as NASCAR heads toward the second half of the regular season.Ty Gibbs also capitalized on a strong weekend. After sweeping both stages and finishing third behind Van Gisbergen and Chase Briscoe, Gibbs moved up one position to fourth in the standings. The Joe Gibbs Racing driver now sits 130 points behind teammate Hamlin.Christopher Bell gained two positions to crack the top 10 after his fifth-place finish, while William Byron also climbed one spot to 12th.Sonoma Creates New Momentum Heading Into ChicagolandAlthough Hamlins lead is just one point, Sundays race completely reshaped the championship conversation.What had been Reddicks advantage entering Sonoma disappeared in one afternoon, while several drivers around the playoff cut and inside the top 15 continued to shuffle positions after one of the seasons most consequential road course races.With 18 races complete, the Cup Series now heads to Chicagoland Speedway, where Hamlin will try to protect his newly reclaimed points lead and Reddick will look to bounce back from one of his toughest weekends of the season.