Who plays Left Back?

With the news that KATANG (3) is out injured for our game vs AUU we have two choices in the left back position. BABU (5) looked excellent when he came on vs RMUTR, linking defence with attack, with him not only being solid at the back but also offering a threat going forward. However, with the TA starting next week, should we have our minds on that and start with NU (44) on the left? He filled in there last season and although KATANG (3) is not thought to be a long term injury worry, do we need to test back-ups?