(CNN) -- The Netherlands made a winning start to their World Cup Group E campaign on Monday as a moment of defensive madness cost Denmark dearly at Soccer City in Johannesburg.The Dutch failed to live up to their pre-tournament billing as one of the favorites, needing an own-goal from Simon Poulsen less than a minute into the second half to settle their nerves and pave the way for an eventually comfortable 2-0 victory.Dirk Kuyt sealed the win with five minutes left, then defender Poulsen made a spectacular clearance from under his own crossbar to prevent an even more damaging defeat.The Netherlands started the match in South Africa with star forward Arjen Robben on the substitutes' bench still resting his injured hamstring, but still boasted attacking potency in Robin Van Persie and Kuyt plus the midfield presence of Mark van Bommel and Rafael van der Vaart.But Denmark slightly edged the first half as striker Nicklas Bendtner -- who made a surprise recovery from injury to start the match -- headed wide, and then set up Thomas Kahlenburg for a shot that was well saved by Dutch goalkeeper Maarten Stekelenburg.But the game turned some 40-odd seconds after the halftime restart when Poulsen, who plays for Dutch club AZ Alkmaar, inexplicably headed Van Persie's cross onto the back of his helpless teammate Daniel Agger and into the net.With Bendtner going off after an hour, the Danes lost all attacking impetus despite the introduction of 18-year-old forward Christian Eriksen, the youngest player to appear so far at this year's tournament.It became only a matter of time before the Dutch extended their lead, with Wesley Sneijder's deflected shot looping onto the top of Thomas Sorensen's crossbar.Kuyt wrapped it up soon after with a simple chance, following up as Eljero Elia broke free down the left and beat Sorensen with his low shot but hit the post.Poulsen then made some amends for his earlier error as he got back to clear with Sorensen again beaten in the 88th minute.Credit: CNN