The Blazers trailed by two to start the second half, but held the Lakers to 21.7 percent shooting (5 of 23) and blocked four shots in the third quarter, outscoring Los Angeles 23-12.
Damian Lillard overcame an 0-for-8 start to finish with 20 points, eight rebounds and six assists for Portland. Al-Farouq Aminu had 15 rebounds, and Maurice Harkless scored 14 points.
The Lakers shot 38.6 percent for the game. Luol Deng led them with 14 points but did not make a field goal after the first half.
Portland outrebounded the Lakers 29-16 in the second half.