Dublin, Nov 15 (IANS): Denmark fell behind early in the second-leg World Cup playoff here against Ireland before coming back to win 5-1 and punch their ticket for the 2018 tournament in Russia.

Shane Duffy put the hosts ahead 1-0 in the 6th minute, raising the hopes of their supporters among the crowd of 51,000 at Dublin's Aviva Stadium on Tuesday, Efe news reported.

Duffy took advantage of a poor clearance by the Danish defenders after Robbie Brady's free kick to put a header past goalkeeper Kasper Schmeichel.

With their heroes having escaped from the first leg in Copenhagen with a 0-0 draw, the Irish fans could be forgiven for imagining that the side could defend a lead at home.

But things turned sour in the 29th minute, when Denmark's Andreas Christensen scored.

The Danes took the lead three minutes later with a strike from their best player, Christian Eriksen.

The Tottenham Hotspur playmaker went to get two more in the second half, in the 63rd and 74th minutes, respectively, and Nicklas Bendtner converted from the spot in stoppage time to make the final 5-1.

Denmark are headed to the World Cup for the fifth time.