COSTA DO SAUIPE, Brazil (Reuters) - Fifa will go ahead with its controversial decision to stage World Cup matches at mid-day in tropical venues, president Sepp Blatter said on Tuesday as football's governing body announced a bafflingly complex procedure for Friday's draw.

General Secretary Jerome Valcke caused general bewilderment as he tried to explain the workings of the draw which will decide which teams comprise the eight first-round groups at next year's tournament.

"It's not easy to understand it the first time, I agree with you" he said. "It took me some time to be sure I had the right explanation."

Each group will consist of one team from each of four pots with Pot 1 featuring the top seeds: Brazil, the host nation, alongside Colombia, Argentina, Uruguay, Germany, Spain, Belgium and Switzerland.

The other pots will be based on geographical criteria so that countries from the same confederations are kept apart.

Pot 2 will contain the five African teams, Ivory Coast, Ghana, Algeria, Nigeria and Cameroon, plus the non-seeded South American teams Chile and Ecuador and a European team to be moved out of Pot 4 in a pre-draw.

Pot 3 will feature Japan, Iran, South Korea, Australia, United States, Mexico, Costa Rica and Honduras while nine European sides, Bosnia, Croatia, England, Greece, Italy, Netherlands, Portugal, Russia and France, will comprise Pot 4.

Valcke revealed that a pre-draw will be held to move one of the nine European teams into Pot 2 where they would then be drawn against one of the four seeded South American teams to preserve the geographical balance of the draw.