Tanner Smith matched his career high with 17 points and Clemson never trailed in a 69-55 win over Long Beach State on Friday in the Paradise Jam.
The Tigers (3-0) will play Old Dominion in the second round and the 49ers (1-2) will play Saint Peter's.
Clemson, which hit 24 of 48 field goals, has shot 50 percent or better in three straight games to open the season.
The Tigers also shot a season-best 59 percent from 3-point range (10 of 17), with six different players hitting 3-pointers.
Clemson took a 13-point lead in the first half, but Long Beach State closed to 28-24 with 3:50 to go. The Tigers finished the half on a 9-0 run and led by as many as 20 in the second half.
Smith also scored 17 points last year when Clemson defeated the 49ers 87-79 in their only other meeting.
Larry Anderson scored 14 and was the only Long Beach State player in double figures.