A late second-quarter drive capped by Kyren Williams' 1-yard touchdown run gave the Rams their first lead of the day.
The Rams' offense spent most of the first half going nowhere against the Chargers, failing to pick up a single first down until late in the second quarter. Then Matthew Stafford found Tutu Atwell for a 40-yard gain down the left side with 1:26 left before halftime, putting Los Angeles at the Chargers' 17-yard line.
Stafford followed that up by hitting Puka Nacua for 13 yards to the 1-yard line, setting up Kyren Williams, who bounced his way into the end zone for a 1-yard score. Brandon McManus added the extra point, and the Rams took a 10-9 lead into the locker room.
Stafford finished the half 10-of-14 for 95 yards with an interception mixed in among the late heroics. Nacua paced the receivers with seven catches for 40 yards as the Rams' passing game finally found some rhythm after a sluggish start.
The one-point margin sets up a tight second half between the two Los Angeles teams sharing SoFi Stadium.