Six Clippers scored in double digits. Cuttino Mobley, in his preseason debut after missing the first four games because of a strained left calf, was 0-for-3 from the field in 16 minutes.
Grant Hill led the Suns with 17 points, while Steve Nash had 11 points and six assists. Boris Diaw, starting at center while Amare Stoudemire recovers from arthroscopic surgery on his right knee, had seven points and three rebounds in 27 minutes.
Marcus Banks scored 13 of his 16 points in the fourth quarter to lead a furious comeback that just fell short.
Clippers coach Mike Dunleavy rested his starters the entire fourth quarter, and the reserves were overwhelmed by the Suns' bench players down the stretch. Trailing by as many as 23 early in the fourth, Phoenix narrowed the gap to 104-93 with 5:39 to play. Banks helped fuel the 22-7 run with nine points in a 2:39 span and Richie Frahm capped it with two free throws and a pair of 3-pointers.
The Suns got as close as 106-103 on Alondo Tucker's 3-pointer with 1:10 left. But the Clippers sealed the victory with two free throws by Josh Powell and a layup by Dan Dickau in the final 57 seconds.
The first two players off the Phoenix bench each picked up four fouls during the first 15 minutes of the game. Backup center Sean Marks got all of his during a 3:16 span of the opening quarter. Leandro Barbosa, the NBA's Sixth Man of the Year last season, got his fourth with 9:02 left in the half and the Suns trailing 42-36.
Moments after Barbosa left the court with his fourth foul, the Clippers went on a 21-6 run that extended a five-point lead to 65-45 with 1:17 left in the second quarter.
Thornton, the 14th overall pick in the June draft, paced Los Angeles to a 67-51 lead at halftime with 16 points.
Los Angeles took a 35-29 lead on Dickau's four-point play with 11.5 seconds left in the first quarter. He drained a 3-pointer right in front of the Clippers' bench while getting hammered by Barbosa, then got up and sank the free throw.
Dickau, the former Gonzaga star, is playing for his seventh NBA team in six seasons -- not counting the New York Knicks, who acquired him in a draft-day trade from Portland and waived him on Oct. 2 after completing a buyout of his contract.