Sylvester Stallone in 'The Expendables'The aging warriors of 'The Expendables' fended off five new challengers to maintain the No. 1 spot at the box office for a second week in a row. Of the five newcomers, only 'Vampires Suck' and 'Lottery Ticket' met pre-release expectations.

Even with the addition of 'Piranha 3D' this week, 'Expendables' remained the pulpy thrill machine of choice for moviegoers, earning another $16.5 million, according to studio estimates. Word of mouth for Sylvester Stallone's action hit remained strong, leading to an estimated 10-day total of $64.9 million.

'Vampires Suck' opened at No. 2 as the weekend's top comedy. The 'Twilight' spoof opened wide, on 3,233 screens, taking in an estimated $12.2 million from Friday to Sunday. Added to the two extra days of cash it earned by opening on Wednesday, the movie's total take so far is $18.6 million. Sylvester Stallone in 'The Expendables'The aging warriors of 'The Expendables' fended off five new challengers to maintain the No. 1 spot at the box office for a second week in a row. Of the five newcomers, only 'Vampires Suck' and 'Lottery Ticket' met pre-release expectations.

Even with the addition of 'Piranha 3D' this week, 'Expendables' remained the pulpy thrill machine of choice for moviegoers, earning another $16.5 million, according to studio estimates. Word of mouth for Sylvester Stallone's action hit remained strong, leading to an estimated 10-day total of $64.9 million.

'Vampires Suck' opened at No. 2 as the weekend's top comedy. The 'Twilight' spoof opened wide, on 3,233 screens, taking in an estimated $12.2 million from Friday to Sunday. Added to the two extra days of cash it earned by opening on Wednesday, the movie's total take so far is $18.6 million.

Julia Roberts in 'Eat Pray Love''Vampires' edged out last week's second-place movie, 'Eat Pray Love,' by just $200,000. Coming in third, the Julia Roberts travelogue earned an estimated $12.0 million, for a two-weekend take of $47.1 million.

'Lottery Ticket,' opening in fourth place, did better than expected, earning an estimated $11.1 million. The smallest of the five major new releases this week, opening on just 1,973 screens, the comedy also had the best per-screen average ($5,639) among this week's wide releases.

At No. 5 was the action comedy 'The Other Guys,' at an estimated $10.1 million. After three weeks, it's still the widest-release movie currently playing (3,472 screens), with a total to date of $88.2 million.

According to early estimates, 'Piranha 3D' opened just a hair behind 'The Other Guys,' missing out on a top 5 opening by just $65.000. Its $10.035 million marks one of the lowest openings for a 3-D movie this year. Blame the screen count; it debuted in just 2,470 venues. Still, it had a per-theater average of $4.063. Had it played on just 16 more screens, it could have made the top 5.

'Nanny McPhee Returns'
was the only family movie opening this weekend; that, plus its strong reviews and moderately large theater count (2,784 venues), should have helped the film bring in $10 or $11 million. Instead, it made just $8.3 million, according to studio estimates, good for a seventh-place opening.

Jennifer Aniston and Jason Bateman in 'The Switch'The week's final new movie, 'The Switch,' had the biggest star power (Jennifer Aniston, Jason Bateman) but the weakest opening. The romantic comedy averaged $4,026 per screen, nearly the same as 'Piranha 3D,' but it opened on just 2,012 screens, for an estimated total of $8.1 million, just $210,000 behind 'Nanny McPhee Returns.'

Given how close some of these figures are, some movies may switch rankings once final figures are released on Monday.

The full top 10:
1. 'The Expendables,' $16.5 million (3,270 screens), $64.9 million total
2. 'Vampires Suck,' $12.2 million (3,233), $18.6 million
3. 'Eat Pray Love,' $12.0 million (3,082), $47.1 million
4. 'Lottery Ticket,' $11.1 million (1,973), new release
5. 'The Other Guys,' $10.1 million (3,472 screens), $88.2 million
6. 'Piranha 3D,' $10.0 million (2,470), new release
7. 'Nanny McPhee Returns,' $8.3 million (2,784), new release
8. 'The Switch,' $8.1 million (2,012), new release
9. 'Inception,' $7.7 million (2,401), $261.8 million
10, 'Scott Pilgrim vs. the World,' $5.0 million (2,820), $20.7 million

Top 10 movies of summer 2010:
1. 'Toy Story 3,' $403.7 million
2. 'Iron Man 2,' $312.1 million
3. 'The Twilight Saga: Eclipse,' $297.2 million
4. 'Inception,' $261.8 million
5. 'Shrek Forever After,' $237.7 million
6. 'Despicable Me,' $230.7 million
7. 'The Karate Kid,' $174.9 million
8. 'Grown Ups,' $159.0 million
9. 'The Last Airbender,' $130.1 million
10. 'Salt,' $109.9 million

•Follow Gary Susman on Twitter @garysusman.