Grossing north of $55 million, Paramount's sequel "Transformers: Revenge of the Fallen" easily scored the best opening day ever for a Wednesday release at the domestic box office. Previous record-holder was "Harry Potter and the Order of the Phoenix," which grossed $44.2 million in its first day. Par will release an official Wednesday number Thursday morning. "Transformers 2," playing in more than 4,200 theaters in the U.S., has a strong shot at eclipsing the $152.4 million earned by "Spider-Man 2" in its first five days. That film opened on the same Wednesday in 2004. The opening day haul in the U.S. included $16 million in midnight runs, the best run ever for a film released on a Wednesday. And it's the third-best of all time after "The Dark Knight" ($18.5 million) and "Star Wars: Episode III -- Revenge of the Sith" ($16.9 million). The sequel also is cleaning up overseas, where it's now playing in virtually every major territory, save for Italy and India. On Wednesday, film saw boffo opening numbers in both Australia and Korea, two key markets for the franchise. Grossees in each territory exceeded the performance of the original "Transformers." "Revenge of the Fallen" got off to a sizzling start in the U.K. and Japan, where it opened early over the weekend. Pic grossed $19.6 million from 833 runs to top the international B.O. chart for the weekend. In Blighty, pic grossed north of $14 million from 517 locations to come within 3% of the opening of "The Dark Knight" last summer. Sequel outperformed the original "Transformers" by 71% and "Spider-Man 2" by 18%. Action remains a gigantic draw overseas, evidenced by the turnout for the first "Transformers." That film earned $51 million in South Korea alone, followed by $47.5 million in the U.K. Like the domestic box office, the international B.O. is primed for a big-budget action tentpole. Overseas, the highest-grossing summer actioner to date is "Terminator Salvation" ($196.5 million). Last summer a number of Hollywood event pics logged boffo biz. This summer has been sluggish in comparison. Four films last year jumped the $300 million mark, led by "Indiana Jones and the Kingdom of the Crystal Skull" ($401.3 million), "Dark Knight" ($375.1 million) and "Hancock" ($326.2 million). Domestically, estimates have "Transformers: Revenge of the Fallen" grossing $150 million-$170 million over its five-day debut.