The big transfer news surrounding Sunderland has unquestionably been the rabidly-awaited return of Fabio Borini, the former Liverpool man finally signing for Sunderland after garnering immense popularity during his 2013/14 loan spell. But while Borini's arrival has bolstered the Black Cats' attack, serious question marks remain over their defensive options. Sunderland have conceded 10 goals in their four Premier League games so far, and looked extremely lax against League 2 Exeter City in a recent 6-3 League Cup win. Various centre back pairings have been tested, with Younes Kaboul, Sebastian Coates and club captain John O'Shea all culpable for errors. On the flanks, full backs Patrick van Aanholt, Billy Jones and Adam Matthews have looked even less convincing; fans of the Black Cats are already sick of the sight of opposition forwards exploiting huge holes in wide areas, or being given more than enough time to pick out a perfect cross. Further recruitment is clearly needed, but with the transfer deadline day clock ticking, time appears to be rapidly running out. Nevertheless, several options are still available to Dick Advocaat and co., players who could potentially turn around a disastrous start to the season. Here are five emergency defenders Sunderland could sign today.