What happened: Robert Griffin III ranked Kansas City first, followed by San Francisco, Buffalo, Las Vegas and Minnesota after three weeks of play. His list tracks a crowded unbeaten tier across both conferences entering Week 4.

Why it matters: Kansas City's spot at No. 1 gets an immediate test with a road game against Las Vegas, another 3-0 team in the ranking. San Francisco's No. 2 placement also lands as the club plays through owner Jed York's six-game suspension without a change to its contender status.

What to watch: Week 4 will show whether Kansas City can hold the top spot and whether Buffalo, San Francisco and Minnesota keep pace. Another shuffle is likely once the unbeaten group narrows.