article_snippet: Republic of Ireland's Stephen Quinn and Kevin Doyle during the training session at Gannon Park .
article_snippet: Marc Wilson can and has played at full-back, although has more recently been employed as a central defender by Marc Wilson country, while Ciaran Clark is also left-sided and could play in both positions.
article_snippet: Goalkeeper Shay Given (right) trains alongside fellow stopper David Forde .
article_snippet: Republic of Ireland player Daryl Murphy talks to the media during training ahead of the Poland clash .
article_snippet: However, there is a school of thought which suggests that any vacancy on the left side of the back four could be filled by Hull winger Robbie Brady, who has operated there in the past for both club and country.
article_snippet: Indeed, he scored twice from that position in November's 4-1 friendly victory over the United States in Dublin, and that has not been lost on he manager.
article_snippet: O'Neill said: 'O'Neill did very well, really well, scored two goals and from that position on the field, was really excellent.'
article_snippet: Republic of Ireland Ireland assistant manager Roy Keane in action as Republic of Ireland assistant manager Roy Keane in action as his side prepare for the Group D leaders side prepare for the Group D leaders .
article_snippet: Poland currently lead Group D by three points from Germany, Scotland and Ireland, and while O'Neill does not necessarily view Sunday's encounter as a must-win affair, O'Neill knows the impetus a victory would give his side.
highlights_snippet: Republic of Ireland face Poland in at Aviva Stadium in Dublin on Sunday .
  