James McClean has apologised for a Twitter outburst after his non-selection in the Republic of Ireland's opening World Cup qualifier. The Sunderland forward had been struggling with illness earlier in the week and due to that, was named among the substitutes for the Republic's Group C encounter in Kazhakstan. But despite Giovanni Trappatoni's men struggling to a last-gasp 2-1 win against the European minnows, McClean was not called up - much to his frustration. Later on Friday night he took to the social network site to vent his anger with an expletive, also adding: "Delighted as a fan we got the the win... Personal level #fuming #embarrassing." McClean has since deleted the tweet and said sorry for the outburst, stating: "i apologise for my tweet, it was stupid, disrespectful and i let my frustration get the better of me which still aint an excuse."