LeBron James has been ruled out for up to four weeks and will miss the start of the NBA season with sciatica, Los Angeles Lakers have confirmed.

James, 40, signed a new contract with the Lakers in June and is set to become the first player to play across 23 separate NBA seasons.

Sciatica is a pain in the sciatic nerve that goes down the lower back and through the leg.

James has not taken part in pre-season and missed the defeats against the Golden State Warriors and the Phoenix Suns earlier this month because of the glute nerve irritation.

The American is expected to be sidelined for all five of the Lakers’ games in October, including the season-opener against Golden State.

James, the NBA’s all-time leading scorer, has never previously missed the start of the season in his 22-year career.