What position battles defined Ireland rugby in the professional era

Ireland's key position battles in the professional era centered on hooker (where Keith Wood, Shane Byrne, and Rory Best competed for supremacy), scrum-half (Peter Stringer versus Paul Marshall), and fly-half (Jonathan Sexton eventually dominating after years of competition with Ronan O'Gara). The hooker position proved particularly contested given its importance to Irish rugby's physical identity and lineout dominance.