South Africa have confirmed that Eben Etzebeth is the only player in the Springboks' squad that could be ruled out of their opening game at the Rugby World Cup.

Heyneke Meyer has a number of players who are short of match fitness after returning from injuries, including captain Jean de Villiers and scrum-half Fourie du Preez, while Etzebeth has been sidelined by a calf problem.

"[Etzebeth] started running last week and we will progress him this week. A decision on his availability will be made later in the week," Sky Sports News quotes team doctor Craig Roberts as saying.

"Otherwise it is up to the coach to decide who he selects for the game."

South Africa face Japan in their opening match of the tournament in Brighton on Saturday.