Is the 49ers' Biggest Rival the Kansas City Chiefs?

For years, the 49ers' biggest rival was the Dallas Cowboys.

Feb 11, 2024; Paradise, Nevada, USA; San Francisco 49ers quarterback Brock Purdy (13) against the Kansas City Chiefs in Super Bowl LVIII at Allegiant Stadium. Mandatory Credit: Mark J. Rebilas-Imagn Images | Mark J. Rebilas-Imagn Images

For years, the 49ers' biggest rival was the Dallas Cowboys.

Then, the Cowboys embraced relentless mediocrity, and the 49ers' rival became the Seattle Seahawks. Then, the Legion of Boom got old, and the 49ers' rival became the Rams, a rivalry which only intensified when the Rams moved from St. Louis back to Los Angeles.

But during the past five years, the 49ers' biggest games have come against the Kansas City Chiefs, with the Chiefs winning all of them. That's why Sports Illustrated says the Chiefs are the 49ers' biggest rival.

"Maybe the correct answer here is the Rams, but Shanahan and 49ers players might spend the rest of their lives thinking about the two Super Bowl losses to the Chiefs," writes Sports Illustrated's Gilberto Manzano.

"It might sting more knowing that Philadelphia managed to avenge its 2023 Super Bowl loss to Kansas City with a blowout victory in February. San Francisco had Kansas City on the ropes twice and couldn’t finish the job on the biggest stage either time.

"The 49ers’ Super Bowl window might not be completely shut, but they lost plenty of talent in the offseason after missing the postseason in 2024. Oh, what could have been had Shanahan not elected to receive the ball first in overtime of Super Bowl LVIII."

Or, if Shanahan hadn't abandoned the run in the third quarter when the 49ers had the lead. That's when Shanahan called 11 passes and just 3 runs despite having prime, pre-bilateral-Achilles-tendonitis Christian McCaffrey in the backfield.

Which means the Chiefs are not the 49ers' biggest rival. The 49ers beat themselves in those Super Bowls. Their rival is the ability to finish.