The Blazers played their usual starters, minus LaMarcus Alrdridge, for about a quarter each. Robin Lopez, who saw the most time at just over 14 minutes, recorded 15 points with nine rebounds.
C.J. McCollum and Victor Claver each contributed 12 points in the win.
Portland (54-28) was locked in the fifth spot in the Western Conference and will travel to Houston for its first-round matchup on Sunday.
LA had a slim chance to lock up the No. 2 seed in the West, but needed lowly Detroit to defeat Oklahoma City earlier in the night.
The Pistons gave it a good effort, but eventually fell 112-111. Los Angeles (57-25) will settle for the No. 3 seed and host the Golden State Warriors on Saturday.
The Clippers were without Blake Griffin, JJ Redick and Chris Paul. Griffing was suspended for the game because he picked up his 16th technical foul of the season on Tuesday, while Redick and Paul were held out to rest.