The San Francisco 49ers routed the Cleveland Browns by a score of 31-3 on Monday night, and afterward, 49ers rookie defensive lineman Nick Bosa planted a Niners flag in the end zone.

If you were wondering just what message Bosa was trying to send, it's something that dates back to his college days.

Back in 2017, when Bosa was at Ohio State, Baker Mayfield's Oklahoma Sooners defeated the Buckeyes at Ohio State, and to mark the victory, Mayfield staked a Sooners flag at midfield.

After the game, Bosa said he had planned to do the flag-planting stunt all week, according to Tim Kawakami of The Athletic.

Bosa had a big game to boot, logging four tackles, a couple of sacks and a forced fumble. Meanwhile, Mayfield had what was probably his worst game as a pro, completing just eight of his 22 passes for 100 yards and a pair of interceptions.

The 49ers improved to a surprising 4-0 with the win, maintaining their grasp on sole possession of first place in the NFC West.

As for the Browns? Just when it looked like they were turning things around with a 40-25 win over the Baltimore Ravens last weekend, they turned in their most lifeless performance of the season thus far at Levi's Stadium.

As poorly as Cleveland played in its season opener, when it fell by a score of 43-13 to the Tennessee Titans, this outing was probably worse, as the Browns' vaunted offense mustered just 180 total yards while their defense surrendered 275 rushing yards.

Cleveland will now head back home to host the Seattle Seahawks next Sunday while San Francisco will trek on the road for a pivotal NFC West showdown against the Los Angeles Rams.