The initial optimism that Springbok lock Victor Matfield will be ready for Saturday's Tri-Nations Test against Australia at Loftus Versfeld in Pretoria made way for a more pessimistic view on Monday.

Matfield was a massive presence for the home side in the lineouts and as receiver of kick-offs until he had to leave the field after a blow to the head as he was tackling All Black skipper Anton Oliver.

He looked decidedly shaken as he was helped off but concussion, that would mean a mandatory lay off, has not been diagnosed. Springbok coach Harry Viljoen after the match said Matfield suffered double vision and bad bruising. On Sunday the Bok camp said Matfield should be ready for the Wallaby encounter.

However, on Monday Springbok spokesperson Mark Keohane said it seems Matfield's injury has deteriorated overnight. "It doesn't look good and Harry is extremely worried about the eye. It got worse overnight."

Matfield has another couple of days to recover and after his commanding performance in his first start for his country Viljoen would want to give him as much chance as possible to recover.

Centre Marius Joubert's knee injury will be reassessed on Friday. The Boland player injured his knee after 19 minutes of his debut Test and will miss the game against Australia. Keohane said no replacement would be called upon and that a decision about Joubert's availability for the Springboks' overseas leg of the Tri-Nations campaign would be made after the assessment.

Western Province flyhalf Braam van Straaten will now certainly slot in at inside centre and will also take over the goalkicking duties from Percy Montgomery, with Robbie Fleck moving to outside centre.

Meanwhile it was all good news for the All Blacks as they returned to New Zealand.

Both Jeff Wilson, who was replaced at halftime suffering from double vision and a migraine, and Norm Maxwell, suffering from hurt ribs, should be fine for their next Tri-Nations clash against Australia in Dunedin on August 11.