Sunderland boss Roy Keane has confirmed Liam Miller was transfer-listed because of poor time-keeping. The 27-year-old Republic of Ireland international was told he could leave the club yesterday after arriving late for training on several occasions. Keane, who once left three players behind on Wearside after they turned up late for the bus to an away match, had little hesitation in asserting his authority once again. He said: 'The problem is Liam's time-keeping, it is as simple as that. It is nothing to do with Liam as a player or as a lad. 'I have got a lot of time for Liam, but we set a very high standard at the football club and unfortunately, Liam has not been unable to match that, so we have put him on the transfer list and we will see what happens. 'You have got to be on time for training. If a player is late once or twice, well and good; if he is late three or four times, maybe well and good. 'But when it goes beyond five, six, seven times, then you have got to draw the line. In any walk of life, you have got to be on time. 'We had an incident last year when players were late for the bus, and you move on. We cannot wait for anybody at the club.' Miller played in the reserves' 1-0 defeat at Bolton last night on his return from a calf injury hours after being told of the decision, although it remains to be seen whether he will be included in the senior squad for Saturday's Premier League trip to Derby. However, while his future looks bleak on Wearside, Keane has not entirely closed the door on him. He said: 'Liam played last night and if he performs like he did last night and nobody comes in for him, then who knows? 'As long as he is under the roof, you feel, as with lots of other players, they have always got a chance. 'We have got a lot of other players who have not been involved in the first team for the last few months, but if they keep working hard, then you never know when they will get the opportunity.'