Jordan McLaughlin scored 19 points in his college debut for the Trojans, who briefly took a one-point lead in the second half but could never stretch it out. Coach Andy Enfield started his second season with a loss, just like last year, when USC went 11-21 and won just two Pac-12 games.
The Vikings answered with seven consecutive points, highlighted by Bamba's 3-pointer and his steal and fastbreak layup that put them ahead 54-48. It was part of a dominant closing stretch that eventually saw the Vikings lead by 12.
Bamba sat out last season while recovering from an Achilles' injury after attending two junior colleges.
USC closed within one on a basket by Reinhardt with 7:16 to play. But the Vikings maintained their steady offense, going on a late 10-0 run in which Tucker and DaShaun Wiggins scored four points each.
The Vikings opened the game on a 19-12 run that produced a seven-point lead. The Trojans outscored them 11-3, including a 3-pointer by McLaughlin, to take a 23-22 lead.
But Portland State ran off 13 unanswered points, with Douglas hitting two 3-pointers, as part of a 17-9 spurt that sent the Pilots into halftime leading 39-32.
Portland St.: The Vikings had just four turnovers. ... Lost to USC 87-78 in the schools' first meeting on Jan. 20, 1978. ... The Vikings were 17-15 last season.
USC: The Trojans committed 23 turnovers and outshot the Vikings 53 percent to 39 percent.
Portland St.: Host Willamette on Tuesday.
USC: Host Tennessee Tech on Monday.