The winless Los Angeles Rams were fresh off a 31-point setback and missing two major talents when they hit the field against a rival that had crushed them for a half-decade.

The side would fall behind San Francisco by 14 points in the second half, and they still trailed by double digits midway through the fourth quarter.

From there, the Rams pulled off a dramatic 27-24 comeback in a performance that star quarterback Matthew Stafford puts right up there with his best victories.

“I’m not into unlikely,” he remarked post-game.

“NFL is an improbable business, I’ll tell you that much.

“You never know what’s gonna happen week in and week out. You’ve got to go out there and earn it and prove it, and we accomplished that.”

Kyren Williams raced four yards to score his third touchdown of the day with 1:51 remaining before Joshua Karty nailed a 37-yard from goal with two seconds remaining to win the game for Los Angeles.

The outcome matched their franchise’s best second-half comeback triumph since 2006.

“I think there are the games where you bring just a little bit more juice,” Williams said.

“Just the games where you can’t wait to play, everybody’s doubting you and everybody’s (saying), ‘There’s no way the Rams are gonna win. The Rams are gonna start 0-3.’

“We feel it for sure, but it’s something that fuels us.”

49ers quarterback Brock Purdy finished 292 passing yards, but it wasn’t enough for the Super Bowl favourites to escape with the win, bringing their record to 1-2 for the year.

“Plenty of opportunities,” defensive end Nick Bosa said.

“I can only speak for myself, and it wasn’t good enough. We’ve got to close them out when we have a chance. … It’s definitely a rough start, but we’ve been through some tough stretches before, but we just have to stay together.”

Both teams were missing most of their top offensive playmakers due to injury.

The 49ers played without Christian McCaffrey, Deebo Samuel and George Kittle, while the Rams were without Cooper Kupp, Puka Nacua and Tyler Higbee.