McCollum scored a playoff career-best 41 points, and Lillard had 34, but the Warriors made the crucial big plays on both ends down the stretch with Portland playing without injured center Jusuf Nurkic.
Draymond Green contributed 19 points, 12 rebounds, nine assists and five blocked shots to help last season's second-place team take the first step in what it is counting on to be a championship run.
Durant shot 12 for 20, showing no issues with a recent left knee injury that sidelined him 19 games before he returned for the final three regular-season contests with the NBA-best Warriors. He patted his chest after two straight fourth-quarter baskets and said, "I got this!"
Game 2 is Wednesday night at Oracle Arena.
The opener in a rematch of last season's Western Conference semifinals won in five games by Golden State didn't disappoint featuring two of the NBA's best backcourt duos. There was a little of everything: physical play, trash talk, deep 3-pointers, monster blocked shots and dazzling dunks. After one flurry of a third-quarter sequence when several players on both teams hit the floor trying to secure a loose ball, four towel guys frantically wiped down the court from the sweat.
Durant got going fast. KD drove the lane for a one-handed slam midway through the first then knocked down a 3 from the top about a minute later. After missing a dunk but getting fouled, Durant pounded the basket stanchion with his right fist in frustration.
He vowed to take his game to another level as a new season begins - not to mention the quest for his first title.
Curry's baseline 3-pointer with 3:30 left in the third followed by Durant's driving layup and three-point play got Golden State going at last, and the teams headed into the final quarter tied at 88.
Curry reached his hand in the air to further ignite the sellout crowd, thrilled to be inside raucous Oracle Arena on a rainy day that postponed the Astros-Athletics game next-door.
As the final period got underway, Ian Clark did what he often does to give the Blazers fits. The 6-foot-3 guard scored a putback off his own miss in the paint one possession then knocked down a 3-pointer the next as Golden State went ahead 97-90 with 8:59 remaining.
McCollum shot 11 of 15 in the first half then began the second 2 for 7 and finished his day 16 of 28 while Lillard shot 12 for 26.
The shot-making tandem combined for 48 of their team's 56 points through halftime as was tied. They averaged an NBA-best for backcourts this season with 50 points per game between them.
McCollum's 27 first-half points matched a Portland playoff record for a half.
Meanwhile, Curry, Durant and Klay Thompson went 12 of 29 in the first half. Thompson wound up with 15 points.
Two-time reigning NBA MVP Curry missed the initial three games against the Blazers last year following a fluke sprained right knee injury suffered in Game 4 at Houston when he slipped on a wet spot.
Green emphatically blocked a shot by Noah Vonleh in the third as the Portland center was going up with one hand to dunk.
Lillard only played one game at Oracle this season because of an injury.
But he was part of a 135-90 debacle on Dec. 17 here - the Warriors' largest margin of victory in the rivalry - that prompted coach Terry Stotts to say afterward, "It's embarrassing to get beat by 45."
PHOTOS: Golden State Warriors fans 2016-2017
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