Stephen Curry added 11 points and had six assists while Andris Biedrins had eight points and 11 rebounds for the Warriors (3-2), who rallied from 11 points down in the first half.
LaMarcus Aldridge scored 11 points for Portland, all but two coming in the first half. Andre Miller added 10 points and four assists for the Blazers (2-4).
Lee, Golden State's most significant offseason acquisition under first-year coach Keith Smart, got off to a slow start but had 10 points during the third quarter when the Warriors slowly pulled away.
Ellis also scored 10 points in the period while Curry made a 3-pointer at the buzzer to give Golden State a 73-59 lead.
Smart emptied his bench early in the fourth quarter but kept Ellis and Lee on the court so the two veterans could continue to get comfortable playing together.
Earlier Monday, Golden State forward Lou Amundson, another offseason addition, underwent surgery on his fractured right index finger. No timetable for his return has been set though Amundson, who also dislocated his knuckle on the same finger when he injured it Saturday night against Portland, could be sidelined up to three months.
Portland, which beat Golden State 118-105 at the Rose Garden on Saturday, was out of sync offensively the entire game. The Blazers shot just 28.6 percent from the field in the first half and committed 13 turnovers that led to 15 points.
It didn't get any better in the second half.
Playing without center Marcus Camby (bruised hip), Portland grabbed only 10 offensive rebounds and had only one blocked shot compared to five for Golden State.
The Warriors trailed by as many as 11 points before closing the second quarter on a 15-5 run to close within 43-42. Lee had five points and Curry added four during the burst.
Curry, who talked before the game about playing more under control after committing eight turnovers in the loss to Portland on Saturday, had three steals and four assists in the first half but turned the ball over five times before intermission and had six total.
Neither team shot well from beyond the arc: the Blazers were 3 of 14 while the Warriors went 4 of 19.
Camby traveled with the team and sat on the bench in uniform but did not play. The Blazers are already thin in the middle with Greg Oden (knee), Jeff Pryzbilla (knee) and Jeff Pendergraph (knee) all sidelined. ... San Francisco 49ers running back Frank Gore sat courtside for the game.