Denmark beat struggling rivals Sweden 1-0 with a first-half goal from Thomas Kahlenberg to move three points clear at the top of World Cup qualifying Group One on Saturday.

Kahlenberg took advantage of a mistake from Sweden defender Mikael Nilsson midway through the first half to fire the ball past goalkeeper Andreas Isaksson.

The win puts the Danes on 16 points from six matches, three ahead of Hungary in second place.

"It was an important step, but we're not there (in South Africa) yet," Denmark coach Morten Olsen told reporters.

"Physically, we're in good shape and that's decisive in a match like this one. All the players are satisfied, it was a fantastic match."

Things are looking less promising for the Swedes, who missed a penalty in the Denmark game and are down in fourth place with six points from five matches.

The group winners qualify for the finals directly while the best eight runners-up from the nine groups go through to a play-off.

"We played a good game and we created enough goal chances. I think we lost in a cruel manner," said Sweden coach Lars Lagerback.

"We had the margins against us. The first half was even and then the guys played a really good second half, and normally we would get the ball in," Lagerback said.

"Realistically, we're setting our sights on second place and qualifying. We still have all the possibilities of advancing."

PENALTY MISS

Sweden were awarded a penalty in the 12th minute but failed to capitalise as Kim Kallstrom's weak effort was easily saved by Thomas Sorensen.

After taking the lead, the Danes should have made it 2-0 in the 30th minute when Dennis Rommedahl missed an open goal from less than a metre out.

"It became a physical match and we fought incredibly. We had some luck, and they had some chances but not many clear ones," added Olsen.

"We didn't see much of Zlatan (Ibrahimovic), and we didn't see much of (Christian) Wilhelmsson. We're happy we won. All in all, it was a good performance."

Ibrahimovic, who was Serie A top scorer this season, had an uninspiring night and failed to make an impact on the game.

"We were two against one versus Zlatan all the time. And when he got inside the box, (Daniel) Agger and (Simon) Kjaer were better than him in the air," Olsen said.