SYDNEY - South Africa could be without frontline spin bowler Imran Tahir for the fourth one-dayer against Australia at the Melbourne Cricket Ground after he injured his knee in the 73-run defeat in Canberra on Wednesday.

The 35-year-old leg spinner did not bat in the loss at Manuka Oval, which left the tourists 2-1 down in the World Cup warm-up series with matches to come in Melbourne on Friday and Sydney on Sunday. "I think he sprained his knee a little bit," Proteas skipper AB de Villiers told reporters in Canberra.

"We'll assess him over the next day and see what he's like on Thursday night and make the call on the morning of the game. "I'm not sure how serious it is."

South Africa are already without part-time spin option in all rounder JP Duminy, who was ruled out for the series when he aggravated a long-standing knee problem during the Twenty20 series against Australia.

The 30-year-old should be sidelined for about six weeks and has returned to South Africa for intensive treatment to ensure he is fit for the Feb. 14-March 29 World Cup.

"That's why he went home, to get ready for end of the year cricket and that World Cup," De Villiers added. "He plays a big part in our team. It really balances the team nicely when he's here, it gives us that extra option.

"Obviously his finishing ability in that middle order is priceless, looking forward to getting him back at the end of the year."