Ruddock - a surprise replacement as Welsh coach Steve Hansen just twelve months ago - also talked up his former Leinster players Brian O'Driscoll and Malcolm O'Kelly.
"Brian O'Driscoll's reputation goes before him, as the Ireland captain he leads from the front on the pitch and he will be a certainty for the British Lions tour," admitted the 45-year-old - who assumed the Leinster director of rugby role from 1997 to 2000.
"Paul O'Connell and Malcolm O'Kelly provide an immense physical presence and rugby know how to the side. In the line-out in particular they will present a huge challenge.
With Ireland unbeaten in Cardiff for 22 years, Ruddock - who named an unchanged line-up as his side attempt an historic Grand Slam - added: "The Irish are the most dangerous side we've faced this Championship - technically the most proficient, well prepared through the work of their excellent coaching staff and undoubtedly our biggest challenge to date.
"Their consistency and strength must be respected, however, we must not live in fear of the opposition, we have respect but no fear."