It was young Morant - named NBA Rookie of the Year in 2020 - who showed the way for Memphis with 30 points, seven rebounds and five assists.
For a long time, the match was a showdown between Morant and the home team's superstar Stephen Curry, who was noted for 36 points, seven rebounds and eight assists for the losing team.
Golden State had won all four games before tonight's round.
They led with ten points at halftime and 19 points at most.
Still, thanks to Morant, the guests managed to turn the tables.
At 98-98 and one second left on the clock, Stephen Curry had the chance to decide the match, but missed.
Curry pointless at the end
He also went scoreless throughout the fourth period and in overtime, where Morant shone with 23 of his 30 points.
- I'm a little critical of myself and my last three shots.
My last two during regular time, where I had tried to shoot every day of the week, but in the long run I wanted a little too much, says Curry afterwards.
Despite last night's loss, Golden State, second in the Western Conference, has had its best start since the 2015/2016 season when they won their first 24 matches.
Yes Morant averages 30 points per match so far and is thus split second in the statistics.
Philadelphia's Joel Embiid has the same average and Stephen Curry tops with 36 points per game.
Morant is also divided number one in the statistics for most steals per match (four).