The Dark Knight demolition derby continued apace as Warner Bros' world-beating action epic grossed an estimated $75.6m to set a new second weekend record and crossed $300m in another new mark of 10 days.

Christopher Nolan's phenomenon currently stands at $314.2m and trails Iron Man by a whisker as the second biggest domestic release of the year. Warner Bros distribution chief Dan Fellman said the film may cross $400m in 18 days, shattering Shrek 2's previous best of 43 days. The last film to cross $400m was Pirates Of The Caribbean: Dead Man's Chest two years ago.

This huge second weekend was fuelled by weighty repeat business and consigned to history Shrek 2's previous best second weekend tally of $72.2m. The Dark Knight clearly has a strong chance of setting a new third weekend record if it surpasses Spider-Man's $45m.

Titanic set the all-time high for the fourth through 12th weekends en route to reaching $600.8m, which remains the highest lifetime domestic gross in history. Only time will tell if The Dark Knight has the chops to overhaul that extraordinary achievement.

Once again IMAX played a noteworthy part in proceedings as the 94 North American screens accounted for $4.6m and a magnificent $48,500 per-screen average.

The domestic tally stands at a record $16.3m and IMAX Filmed Entertainment chairman and president Greg Foster said he expected the worldwide tally to reach $20m by Monday in a record 11 days. Harry Potter And The Order Of The Phoenix did it in 16 days and no doubt there'll be some friendly rivalry going on within the Warner Bros fold as Harry Potter And The Half-Blood Prince will seek to reclaim the record for the children's fantasy franchise come November.

'We're in uncharted territory,' Foster said. 'These numbers have been huge for us and obviously we've hitched our wagon to the perfect movie and distributor.'

Sony's comedy Step Brothers starring Will Ferrell and John C Reilly launched in second place on $30m, while Fox's sci-fi sequel The X-Files: I want To Believe opened in fourth on $10.2m. Third place went to Universal's musical Mamma Mia!, which in its second weekend added $17.9m for a very handy $62.7m.

New Line's Journey To The Centre Of The Earth ranks fifth and is also delivering solid numbers as $9.4m raised the tally to $60.2m after three weekends. Sony's Hancock crossed $200m in its fourth weekend, becoming the fourth release of Will Smith's career to do so. Hancock ranks sixth and added $8.2m for $206.4m.

Buena Vista's Wall-E ranks seventh after five weekends and will cross $200m either this week or next weekend after it raised its cumulative tally by $6.3m to $195.2m.

Paramount Vantage opened its hit Sundance acquisition American Teen in New York and Los Angeles in 25th place on $42,827 for a per-screen average of $8,565. The documentary about the trials and tribulations of high school students will expand into the remaining to 12 markets next weekend.

Guillaume Canet's French thriller Tell No One added $267,673 from 70 screens in its fourth weekend through Music Box and ranks 16th on $1.7m. Miramax's feature version of the classic English television drama Brideshead Revisited opened in 19th place on $332,000 from 33 theatres for a $10,060 per-screen average.

Next weekend's wide releases are: Universal's first instalment in the Mummy action franchise in seven years with The Mummy: Tomb Of The Dragon Emperor starring Brendan Fraser, Jet Li, Michelle Yeoh, Maria Bello and John Hannah, and Disney's political satire Swing Vote starring Kevin Costner.

Estimated Top 10 North America Jul 25-27, 2008
Film (Dist)/Int'l dist/Est wkd gross/Est total to date
1 (1) The Dark Knight (Warner Bros) WBPI $75.6m $314.2m
2 (-) Step Brothers (Sony) SPRI $30m -
3 (2) Mamma Mia! (Universal) UPI $17.9m $62.7m
4 (-) The X-Files: I Want To Believe (Fox) Fox Int'l $10.2m -
5 (4) Journey To The Centre Of The Earth (New Line) NLI $9.4m $60.2m
6 (3) Hancock (Sony) SPRI $8.2m $206.4m
7 (6) Wall-E (Buena Vista) WDSMPI $6.3m $195.2m
8 (5) Hellboy II: The Golden Army (Universal) UPI $4.9m $65.9m
9 (7) Space Chimps (Fox) Fox Int'l $4.4m $16m
10 (8) Wanted (Universal) UPI $2.7m $128.6m