Martin O'Neill's side are within touching distance of their first World Cup finals in 15 years as they head home for the second leg.
The Republic of Ireland’s hopes of qualifying for their first World Cup since 2002 were given a boost as they held Denmark to a goalless draw in Copenhagen.
Despite a few first half chances, neither team were able to get the better of their opponents. Eyes now turn to Dublin for the second leg decider on Tuesday.
Martin O’Neill’s well-organised squad will determine their World Cup fate at home and with a full squad as none of the eight Irish players who started the match on a yellow card received another one.
Midfielder David Meyler, who was forced to sit out the match in Copenhagen, will return from suspension, giving the Republic of Ireland a boost that may clinch them victory.
Elsewhere, Sweden shocked Italy in Solna claiming a 1-0 victory over the four-time champions who have not failed to qualify for the tournament since 1958.
Meanwhile Greece were soundly beaten 4-1 by Croatia in Zagreb, and Northern Irish hopes of a first World Cup finals since 1986 took a blow when they lost to Switzerland in Belfast.