Fred Warner’s forced fumble on Alvin Kamara, paired with Kyle Shanahan’s rare successful challenge, flipped San Francisco’s 26-21 win over New Orleans and sparked a momentum swing that carried the 2-0 start. The offense answered with a TD and the defense clamped down late as the 49ers dodged a scare. Next up: a home date with the Cardinals, a key early-season test for fantasy rosters.