For millions of video game players, Christmas arrives this morning as they get to unwrap what's expected to be the biggest release of the year, Call of Duty: Modern Warfare 2.

Across the country, fans stayed up late Monday night to secure the action-shooting sequel to 2007's Call of Duty 4: Modern Warfare during midnight sales events at game stores and big retailers including Best Buy and Walmart.

With millions of copies expected to be sold today alone, the arrival of MW2 (Xbox 360, PS3 and PCs; rated M for ages 17-up, $60 and up) is enough to spawn a holiday of its own. "If I were a boss, I wouldn't bat an eyebrow if suddenly the incidence of sick days went up," says Scott Steinberg of DigitalTrends.com.

Publisher Activision has run a series of movie-quality trailers on prime-time TV in hopes of generating the biggest launch of any entertainment property. "It's going to be monstrous," says John Davison of GamePro Media.

The fastest seller globally to date, Grand Theft Auto IV, brought in $310 million on its first day more than top book Harry Potter and the Deathly Hallows (2007) sold in its first day worldwide ($220 million) and $500 million in the first week, more than top film Harry Potter and the Half-Blood Prince (2009) took in its opening five days worldwide ($394 billion).

Analyst Michael Pachter of Wedbush Morgan Securities says MW2 is an odds-on favorite to set a first-day record and perhaps sell 12 million copies this year. "Aside from the hype and the fact that it is a good game," pre-orders are off the charts, he says. MW2 is the most pre-ordered game ever at GameStop and Game Crazy stores. "Some stores have more than 1,000 reservations," GameStop's Tony Bartel says.

To set a record, Modern Warfare 2 will have to expand its core audience, says Anita Frazier of market tracking firm The NPD Group. The 2007 Modern Warfare sold 2.3 million units in the USA in its first month, according to NPD.

But more people own Xbox 360s and PS3s now, and pricier editions include a $150 set with night-vision goggles. "It has a good shot," says Geoff Keighley of Spike's GameTrailers.