It was an even meeting in Boston and even though the home team led most of the match, it was the guests who took it all home.
In the end, the profit margin was only ten points for the Warriors (107-97).
The best scorer was, as usual, Stephen Curry (43 points), teammate Andrew Wiggins took the most rebounds (16) and Draymond Green is noted for the most assists (eight).
The play-off matches are decided in the best of seven and the teams meet next night towards Tuesday Swedish time.
Then at Golden States home in San Francisco.
This year, the Boston Celtics have a chance to become the NBA's most champion team.
The club already has 17 titles - the first came in 1957. The Los Angeles Lakers have the same number, although five of them came in the 1940s and 1950s when the club was based in Minneapolis.
However, it has been a while since Boston became champions - most recently in 2008. Golden State, with a total of six championship titles, has dominated in recent years.
The team has reached the final six times since 2015 (including this year) and won three times, in 2015, 2017 and 2018.