James Harden has left the Brooklyn Nets' opening game of their Conference semi-final against the Milwaukee Bucks after re-injuring his right hamstring.

Harden was forced off the court after only 43 seconds in Saturday's clash at Brooklyn's Barclays Center.

The Nets confirmed that the 31-year-old was out for the remainder of the game with a right hamstring injury.

Harden left the arena and went for an MRI scan on the same hamstring which kept him out for 21 games late in the regular season.

The shooting guard joined the Nets in January from the Houston Rockets, linking up with Kevin Durant and Kyrie Irving, making Brooklyn one of the NBA title favourites.

The former MVP returned from injury on May 13 against the San Antonio Spurs and played all five games in the Nets' 4-1 series win over the Boston Celtics.

Harden scored 41 points in Game 3 and a triple-double in Game 5, averaging 27.8 points, 7.2 rebounds and 10.6 assists per game in the series.