Juan, the wingback mentioned by GarryKan, seems to be a serious transfer target for Villarreal. He played two years in England earlier in his career before moving back to Brazil, but has lately been on the up, and has been called on by Dunga for the national squad. Notably, he also has Spanish citizenship, which is convenient. He is not afraid of the opponent's goalmouth either - scoring 8 goals in 56 appearances in 2008.
So, a leftback? Not that I wouldn't mind cover there, but with Bruno's play, I have been pretty comfortable with the left side of our defense this year. A centerback seems to be a bit more important at the moment. Of course, with Senna on the slide, Bruno might have to spend a lot more time playing in midfield in the next few weeks.