POLOKWANE, South Africa, June 13 (Reuters) -- A new mixed synthetic pitch being used for the first time at a World Cup finals was criticized by players on Sunday who say it causes unpredictable bounces and gives goalkeepers particular problems.

Both the 1-0 winners of Sunday's Polokwane match Slovenia -- who were propelled to the top of Group C -- and losers Algeria criticised the pitch which contains a mixture of grass and a synthetic fibre.

The same kind of surface will be used for matches played at Nelspruit.

Algerian defender Majid Bougherra said Slovenia's lone goal would never had gone into the net on a pure grass pitch.

The match was settled when skipper Robert Koren's relatively innocuous 79th minute shot bobbled out of Algerian keeper Faouzi Chaouchi's arms.

"Sometimes like the goal scored today -- if we had had a normal pitch it would never have gone in," he said.

"In the last bounce it went quickly and it changed the thinking of the goalkeeper."

Players also complained about the new Jabulani ball being used at the finals, saying it had been particularly difficult to control in a match littered with loose passes.

"For the player when we shoot it's a good ball but for the keeper it's horrible," Bougherra said. "In the air sometimes it changes (course) at the last minute so it's very difficult."

Man-of-the-match Koren said Saturday's goalkeeping gaffe against the United States also in Group C by England's Robert Green -- on grass -- plus Chaouchi's error were largely due to a capricious ball bounce.

Green allowed the U.S. equalizer in a 1-1 draw to run through his fingers from a long-range shot.

"It's really difficult for the keepers because one mistake from the keeper and the ball is already in the net," he said.

"We saw this yesterday when USA scored against England and we saw today when we scored -- it was with a bit of help."

Another seven matches will be played on the mixed synthetic and grass pitches including France against Mexico on June 17 and Greece against Argentina on June 22.

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