It all began back in 2007 when Harbaugh’s Stanford pulled off a jaw-dropping upset against Carroll’s USC Trojans, who were nearly 40-point favorites. But the real competition started in 2009 when Stanford delivered a brutal 55-21 beat down to USC at the LA Memorial Coliseum.

Their rivalry only intensified when Carroll left USC for the NFL’s Seattle Seahawks, just to find himself facing off against Harbaugh’s San Francisco 49ers. The games between these two teams were like heavyweight bouts, with Harbaugh often getting under the Seahawks’ skin. There were even rumors of him honking at their team bus after a victory. The pinnacle of their rivalry came in the 2013 NFC Championship game, a hard-fought battle won by Carroll’s Seahawks.

Now, with Carroll taking on an advisory role with the Seahawks, maybe the rivalry will finally simmer down. But knowing these two fiery personalities, don’t count on it just yet.