In-form Blue Bulls centre Wynand Olivier was called up to join the Springbok squad, ahead of their Tri-Nations opener against the All Blacks in Bloemfontein on Saturday, as cover for injured midfielders Adi Jacobs and Jaque Fourie.

The injuries were revealed by Springbok coach Peter de Villiers earlier on Monday, after the Boks stepped up preparations ahead of the first of their back-to-back encounters with the Kiwis.

The second Test between the two sides is a week later in Durban.

Jacobs, who didn't play in the third Test after two rather forgettable outings against the British and Irish Lions in the first two Tests where his defence in particular was found wanting, is struggling with a groin injury and is the real concern for the Springbok camp.

"He [Jacobs] is basically the only player our staff is working with," De Villiers said at Monday's media conference.

He did add, though, that Jaque Fourie was also receiving what he called "precautionary treatment" for a niggling quad injury.

Added to that, the third centre in the Springbok squad Jean de Villiers was replaced in the second Test against the Lions - he didn't play in the third - and had his arm in a sling after the match.

Coach De Villiers will make a call on Jacobs' availability after his medical staff had made their call - most likely before the match-22 announcement at lunchtime on Tuesday.

Jacobs' injury would not be seen as detrimental to the Springbok cause as the (unlikely) non-availability of Jaque Fourie. His versatility gives De Villiers a player who has top-level experience at fullback and at wing, as well as at inside and outside centre.

Should Fourie have to be replaced before the Test, the Boks will have no cover on the wing or at fullback, although flyhalf-cum-scrumhalf Ruan Pienaar or even one of flyhalf Morne Steyn or wing JP Pietersen would be able to cover there in case of emergency.

But it wouldn't be ideal and could lead to a massive restructuring of the backline.

If Jacobs was injured on Monday, full marks must go to the Boks' coaching staff for acting so swiftly.

If he has, however, carried the injury from last week, it is a repeat of the procrastination with a replacement for Schalk Burger before the first Test against the B&I Lions - despite that fact that the flank couldn't run properly the week before.

Replacement Heinrich Brussow, not part of the initial squad for the Lions series, was subsequently only called up the Monday before the Test with his first full run with the Boks on the Tuesday.

In this instance, however, Olivier was part of the last run-on Test side and has been with the squad since they first assembled for the Lions series which will cause less problems with his slotting in.

However, he was omitted from the initial 23-man squad named by De Villiers last week.