(LOS ANGELES) – Matthew Stafford's second pass for the Los Angeles Rams traveled 53 majestic yards through the air and dropped right into the hands of Van Jefferson, who fell down untouched, stood up and scored. With a dynamic debut against Chicago, Stafford immediately showed the potential the Rams might have unlocked. Stafford passed for 321 yards and three touchdowns in one of the most prolific quarterback debuts with a new team in NFL history, leading the Rams past Andy Dalton and the Bears for a 34-14 victory on Sunday night. Stafford found Jefferson for a 67-yard touchdown on his second pass for the Rams, who swung a blockbuster offseason trade to acquire the 13 year veteran from Detroit. Stafford then hit a wide-open Cooper Kupp for a 56-yard TD to open the third quarter, and he found Robert Woods for a clinching score with 3:17 to play. The Rams scored on six of Stafford's first seven full drives while racking up 375 yards of offense. According to the Elias Sports Bureau, Stafford became the first player with two touchdown passes of more than 50 yards in his debut for a new team since Lee Grosscup did it for the AFL's New York Titans in 1962. Stafford's 156.1 passer rating is the highest in NFL history for a quarterback who had at least 20 pass attempts in a debut with a new team, according to NFL Research. Dalton passed for 206 yards in his Bears debut, and rookie quarterback Justin Fields rushed for a 3 yard score while getting a handful of snaps in his NFL debut. Chicago moved the ball steadily all night, but David Long Jr. intercepted a tipped pass in the end zone on the Bears' opening drive, leaving them playing from behind the rest of the evening. David Montgomery rushed for 108 yards and a touchdown for the Bears, who dropped to 1-3 in season openers under coach Matt Nagy.