Microsoft expect four million people to play Gears of War 3 online this week alone.

Senior product manager Guy Welch expects the number of online gamers to be double that of Gears of War 2, which sold two million copies in its first weekend.

Microsoft predicted that Gears of War 3's dedicated servers will "guarantee (a) smooth launch" for those that go online, as well as expecting 75 per cent of players to go onto XBox Live to play co-operative and multiplayer modes.

Gears of War 3 features four downloadable content packs, which will be discounted as part of a season pass.

There will also be new campaign content available, which will not feature main characters Marcus, Dom or Cole.

Gears of War 3 is released exclusively on XBox 360 worldwide today.

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