Santos, who was plagued by a groin injury during preseason, was a perfect 3-for-3 on field-goal attempts this season and made all 12 of his extra-point tries for the Chiefs (3-0).
The 25-year-old Brazilian misfired on a 51-yard attempt during Sunday's 24-10 victory over the Chargers, but Los Angeles was whistled for a roughing the kicker penalty. Kansas City's offense stayed on the field and Santos made a 34-yard field goal later in the same drive.
Butker, who was a seventh-round selection out of Georgia Tech, was bidding with Graham Gano for the Panthers' kicking job. Butker made both of his field-goal attempts in the preseason, each from beyond 40 yards. He was also 4-for-4 on extra points.