Summer ended with a whimper as Focus Features’ assassin drama The American starring George Clooney opened top on an estimated $12.9m over three days, rising to $16.1m since Wednesday’s [Sept 1] release.

The typically weak conclusion to the blockbuster season is expected to perk up tomorrow when the four-day Labor Day weekend grosses are announced.

Overall summer 2010 is expected to finish ahead of last year’s record season according to tracking company Box Office, which predicted seasonal revenues would climb 2.4% over last year to $4.35bn.

Rising ticket prices and the premium on 3D screenings account for the percentage climb, whereas Box Office estimates summer ticket sales to be around 552m, representing a 2.6% attendance decline from last summer.

Screen gems’ heist thriller Takers fell once place to second on $11.5m for $37.9m after two weekends, while Machete, Robert Rodriguez and Ethan Maniquis’ revenge saga Machete starring Danny Trejo, debuted in third on $11.3m.

The New Line rom-com Going The Distance starring Drew Barrymore and Justin Long opened in fifth on $6.9m through Warner Bros. The Last Exorcism in fourth added $7.6m for $32.5m in its second weekend through Lionsgate.

The Expendables is closing in on $100m through Lionsgate while Inception in ninth stands at $277.1m after eight weeks through Warner Bros.

Next weekend’s wide release is Screen Gems’ Resident Evil: Afterlife 3D with Milla Jovovich and Ali Larter.

Estimated Top 10 North America September 3-5, 2010

Film (Dist) / Est wkd gross / Est total to date

1 (-) The American (Focus Features) FFI $12.9m $16.1m

2 (1) Takers (Screen Gems) SPRI $11.5m $37.9m

3 (-) Machete (Fox) Hyde Park International $11.3m –

4 (2) The Last Exorcism (Lionsgate) StudioCanal $7.6m $32.5m

5 (-) Going The Distance (Warner Bros) WBPI $6.9m –

6 (3) The Expendables (Lionsgate) Nu Image $6.6m $92.2m

7 (5) The Other Guys (Sony) SPRI $5.4m $106.9m

8 (4) Eat Pray Love (Sony) SPRI $4.9m $68.9m

9 (7) Inception (Warner Bros) WBPI $4.5m $277.1m

10 (8) Nanny McPhee Returns (Universal) UPI $3.6m $22.4m