Three days after Doncic destroyed the Phoenix Suns with a virtuoso performance, the Slovenian star found the going harder against a ruthless Golden State at San Francisco's Chase Center.
Dallas had rained in buckets against Phoenix in Arizona on Sunday, but the scoring dried up against the six-time NBA champions.
The Warriors started slowly but pulled clear decisively in the second half after leading 54-45 at half-time.
With Doncic appearing to be nursing a sore shoulder, the Warriors outscored the visitors 34-24 in the third quarter to lead by 19 points heading into the final period.
An 8-0 start to the fourth quarter left the Warriors cruising 27 points clear at 96-69 to effectively put the game out of reach.
Warriors coach Steve Kerr was able to withdraw his starters with five minutes left in the game, earning valuable rest for what could be a long series.
Curry led the scoring with 21 points, 12 rebounds and four assists, while Jordan Poole and Andrew Wiggins had 19 points apiece.
"We did what we were supposed to do -- we won the first game, but there's a lot of work left," Curry said.
"We had a specific game plan coming in and for the most part we executed it. It's going to take that same effort three more times to beat this team.
"They're a really good team. You've got to stay locked in. Hopefully we'll come out on Friday (in game two) and get it done again."
Klay Thompson failed to score a point in the first two quarters but got into the groove in the second half with 15 points. Seven Warriors players finished in double figures.
Doncic led the Mavericks' scoring with 20 points, but cut a disconsolate figure after a defeat where Dallas trailed for almost the entirety of the game.
Dallas somehow had only trailed by nine points at halftime after a wayward shooting performance in the first two quarters.
The Mavs made just 14 of 44 attempts from the field in the first half, and only seven of 29 three-point attempts.
Yet they were able to remain within sight of the Warriors, who shot 22 of 39 but made only five of 18 attempts from beyond the arc.
Thompson made only four attempts from the field in the first half -- and missed them all -- while Curry was also off target from long range, converting only one of six three-point attempts.
The Mavericks pulled to within two points at 35-33 midway through the second quarter, but a brisk 11-2 run, with Curry setting up three-pointers for Poole and Wiggins, saw the Warriors pull clear once more to lay the foundations of victory.
Game two of the series takes place in San Francisco on Friday.
The winner of the Western Conference finals will play the winner of the Eastern Conference, either Boston or Miami, in the NBA Finals.