Pakistan captain Salman Butt defended his side doing without the controversial Decision Review System (DRS), during a batting collapse in the first Test against England, by saying the technology on offer was "not a hundred percent".

The tourists were in the midst of a slump that saw them decline to 47 for six on the second day at Trent Bridge here on Friday when Azhar Ali was given out caught behind for 14 in one of five wickets for James Anderson.