The World Cup organisers have admitted that they were disappointed by worn-looking pitches, but blamed unseasonably cold weather in Germany in May for the problems.

All of the playing surfaces at the 12 World Cup stadiums were replaced at the end of the German league season in mid-May, but low temperatures at that time prevented the grass from growing properly.

World Cup organising committee vice president Niersbach.[filephoto]

"We didn't achieve the optimum objective we set, we have to concede that," Wolfgang Niersbach -- the vice-president of the organising committee -- admitted Thursday.

"This winter there was unsually cold weather in Germany," Niersbach told the daily media briefing.

"In Hamburg, Cologne and Gelsenkirchen the visual appearance is not as good as expected."

Patches may be replaced on the Gelsenkirchen pitch, he added.

Both Hamburg and Gelsenkirchen will host a quarter-final match, although not matches in the last 16.

The design of the two stadiums in question has also not aided the growth of the grass, Niersbach said. The bowl design of the Hamburg stadium, for example, did not let as much light in as the other grounds.

"We are a bit upset, we thought we were so cautious and could offer optimum conditions and we have ended up with a weak spot we were not expecting," Niersbach said.

FIFA President Sepp Blatter said this week that matches at the 2010 World Cup in South Africa could take place on synthetic pitches.

"In the future, it will be necessary to have pitches that can resist all weather conditions," he explained.