Stephen Nell and Pieter Jordaan Johannesburg - Jean de Villiers' injured groin is still being treated, resulting in the Springboks' question surrounding the centre position becoming more difficult.Adi Jacobs has only played one match as replacement since his return from a shoulder injury. This means the possibility of Bryan Habana or Zane Kirchner running out in the Bok number 13 jersey against Ireland in Dublin on Saturday can't be excluded.Earlier in his career, Habana regularly played at outside centre for the Lions and also played there when the Boks lost against Ireland in Dublin in 2006. This option can therefore be considered if the Bok management doubts Jacobs's match fitness and should De Villiers not recover from his groin injury.If Habana and Kirchner are seriously considered for the midfield, it could again bring about a shuffle in the back trio.Habana as Patrick Lambie's centre mate could mean that Kirchner is appointed to fullback, with Gio Aplon and Bjorn Basson as wings.Should Kirchner wear the number 13 jersey, it could mean that Aplon plays fullback and Habana and Basson play wing.Jacobs's only involvement after his return in the Currie Cup series for the Sharks was 32 minutes in a lost league game against the WP at Newlands. Before this he last started on March 27 in a Super 14 game against the Hurricanes in Wellington. He was then replaced by Waylon Murray in the 11th minute after he was injured.It would therefore be wishful thinking to imagine that the 30-year-old is close to match fit and the Bok coach, Peter de Villiers, now has to take a difficult decision about the composition of his midfield.Wynand Olivier, Jaque Fourie and Juan de Jongh are out due to injury.The only positive thing that the Boks can take from this situation, is that their starter team and plans for Ireland will remain secret for now.The bigger the chaos is in the back, the more sense it makes for the Boks to depend elsewhere on established combinations. It means that the Sharks front row of Jannie du Plessis, Bismarck du Plessis and Tendai Mtawarira could be pulled in along with the Blue Bulls lock pair of Bakkies Botha and Victor Matfield.Bismarck is looking forward to wearing the Bok jersey again after regaining his confidence in the Currie Cup after an earlier injury. "It is difficult to come directly back to Test rugby after you’ve been injured," said Bismarck."I had to first play a bit in the Currie Cup. John Plumtree (Sharks coach) helped me to win back a bit of confidence."But he wanted to reveal nothing about the front row. "Adriaan Strauss played good rugby in the Currie Cup and Chiliboy Ralepelle played well in the Tests when he replaced John Smit and later also in the Currie Cup for the Bulls."