Mariota, who hadn't taken a snap this season, took over for Derek Carr, who left late in the first quarter with a significant groin injury. The backup quarterback immediately led the Raiders on a TD drive, culminating with a picture-perfect pass to tight end Darren Waller for the score.
The battle was on.
Herbert put a stamp on his claim for Offensive Rookie of the Year, making splash throw after splash throw. It was the type of performance that underscores the rookie's potential to the Chargers franchise. To do it against one of his favorite quarterbacks was even more special for the young signal-caller.
"Pretty crazy experience," Herbert said about playing against Mariota, via Gilbert Manzano of the L.A. Daily News. "I grew up watching Marcus. He was my favorite player. Just being from Eugene, I knew that program so well. To be able to play a couple games against him, it's been really cool just to see him out on the field. It's everything I've ever wanted."
Mariota and Herbert became the second pair of Oregon alumni since 1948 to face off in an NFL game and each led his team in passing yards. Norm van Brocklin and George Shaw did so six times, per NFL Research.
While Mariota looked like a blast from his younger past, dashing past defenders and dropping soft dimes over coverage, it was Herbert who dove for the game-winning TD in overtime of the 30-27 victory.
Despite putting on a show, the rookie wanted to glow about his counterpart.
"I could look at all of the things he was able to do at Oregon, how athletic and how mobile he was and how accurate he was. ... It was everything I ever wanted to do," Herbert said. "It's just been an awesome experience to be out here and to play against him, one of my heroes."
Herbert did it all for a Chargers offense that insisted on running into a brick wall far too often given that the rookie's right arm was ripping apart a hapless Raiders defense. Herbert showed off his own mobility, throwing darts off the run. Despite a bigger frame, the rookie has deft agility, knows when to escape the pocket and owns the ability to contort his body to get into perfect throwing motion while on the move.
Herbert finished 22-of-32 passing for 314 yards, two TDs and zero INTs, while adding four rushes for 14 yards, including the game-winning touchdown.
A flat-footed bomb to Jalen Guyton set up the victory score and put Herbert over the 300-yard mark for the seventh time this season. It's the most times in NFL history a rookie QB has thrown for 300-plus passing yards.
Herbert is one of five players with 275-plus pass YPG, 25-plus pass TD and 10 or fewer INTs in 2020, entering Sunday. The others make up the MVP discussion: Aaron Rodgers, Patrick Mahomes, Deshaun Watson and Josh Allen.
The rookie phenom has become must-see TV in his first year in L.A.
"I'm excited to see him every week, just like y'all," Chargers cornerback Chris Harris said, via the Las Vegas Review-Journal. "He's adjusting to the time. In November, December, the NFL game is different. Guys start locking in a little bit more, getting ready for the playoffs. Everything gets tighter. He's pushing through that, and that's what you want to see from a rookie quarterback."
Herbert tied the record for most TD passes by a rookie Thursday with his 27th scoring toss of the season.
One thing is for certain, Thursday night's performance is only the beginning.