Ireland open their tournament on Sunday against Wales and will do so without the legendary lock Paul O'Connell following the Toulon tower 's international retirement after last year 's World Cup .
Ireland is the two - time defending Six Nations champions .
Ireland , the two - time defending Six Nations champions , open their tournament on Sunday against Wales and will do so without the legendary lock Paul O'Connell following the Toulon tower 's international retirement after last year 's World Cup .