Clemson moved up two spots, from 17th to 15th, in both The Associated Press Top 25 and the USA Today Coaches' Poll after defeating Boston College on Saturday.
Florida State climbed one position, to third, in the AP poll, and trails only Alabama and Oregon. The Seminoles swapped places with LSU. Georgia and South Carolina are fifth and sixth, followed by Kansas State, West Virginia, Notre Dame and Florida.
Clemson is ranked second among once-beaten teams behind Southern California, which is 13th.
The top eight positions in the coaches' poll remained unchanged.