Blake and Travis Outlaw sank back-to-back 3-pointers midway to erase a 45-41 deficit trough the third period and Portland never trailed from that point.
Brandon Roy scored 16 and had five assists. Outlaw scored 12 with six rebounds, Greg Oden had 12 points and 10 rebounds, and Martell Webster had 10 points and five rebounds for the Trail Blazers, who lost their previous two games to Denver and Houston.
Russell Westbrook led Oklahoma City with 23 points and grabbed four rebounds. Jeff Green scored 19 with 11 rebounds, and Kevin Durant had 16 points and five rebounds for the Thunder, who lost for the first time this season after a 2-0 start.