Oklahoma center Creed Humphrey declared for the NFL draft on Thursday, shortly before Iowa center Tyler Linderbaum announced he would return for the 2021 season.
Linderbaum and Humphrey are ranked as the No. 2 and No. 3 draft-eligible centers by ESPN's Mel Kiper.
Humphrey started for No. 6 Oklahoma in Wednesday's 55-20 win over No. 7 Florida in the Goodyear Cotton Bowl Classic. He started the final 26 games of his career, earning Big 12 offensive lineman of the year honors for the second time this season.