The sci-fi flick "Ender's Game" knocked "Jackass Presents: Bad Grandpa" out of the No. 1 spot at the box office this weekend with an estimated $28 million.

"Bad Grandpa" fell to second place, taking in a still-strong $20.5 million, while "Last Vegas" debuted in third place with $16.5 million.

The top ten:

"Ender's Game," $28M;
"Jackass Presents: Bad Grandpa," $20.5M;
"Last Vegas," $16.5M;
"Free Birds," $16.2M;
"Gravity," $13M;
"Captain Phillips," $8.5M;
"12 Years a Slave," $4.6M;
"Cloudy With a Chance of Meatballs 2," $4.2M;
"Carrie," $3.4M;
"The Counselor," $3.2M